From: Daniel Vetter daniel.vetter@ffwll.ch
Some drivers need to be able to have a perfect race-free fbcon setup. Current drivers only enable hotplug processing after the call to drm_fb_helper_initial_config which leaves a tiny but important race.
This race is especially noticable on embedded platforms where the driver itself enables the voltage for the hdmi output, since only then will monitors (after a bit of delay, as usual) respond by asserting the hpd pin.
Most of the infrastructure is already there with the split-out drm_fb_helper_init. And drm_fb_helper_initial_config already has all the required locking to handle concurrent hpd events since
commit 53f1904bced78d7c00f5d874c662ec3ac85d0f9f Author: Daniel Vetter daniel.vetter@ffwll.ch Date: Thu Mar 20 14:26:35 2014 +0100
drm/fb-helper: improve drm_fb_helper_initial_config locking
The only missing bit is making drm_fb_helper_hotplug_event save against concurrent calls of drm_fb_helper_initial_config. The only unprotected bit is the check for fb_helper->fb.
With that drivers can first initialize the fb helper, then enabel hotplug processing and then set up the initial config all in a completely race-free manner. Update kerneldoc and convert i915 as a proof of concept.
Feature requested by Thierry since his tegra driver atm reliably boots slowly enough to misses the hotplug event for an external hdmi screen, but also reliably boots to quickly for the hpd pin to be asserted when the fb helper calls into the hdmi ->detect function.
Cc: Thierry Reding treding@nvidia.com Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Thierry Reding treding@nvidia.com --- Changes in v3: - remove an additional occurrence of i915's enable_hotplug_processing that was introduced after the original patch
drivers/gpu/drm/drm_fb_helper.c | 11 +++++------ drivers/gpu/drm/i915/i915_dma.c | 3 --- drivers/gpu/drm/i915/i915_drv.c | 2 -- drivers/gpu/drm/i915/i915_drv.h | 1 - drivers/gpu/drm/i915/i915_irq.c | 4 ---- 5 files changed, 5 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index d5d8cea1a679..13a098c9af31 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -1613,8 +1613,10 @@ EXPORT_SYMBOL(drm_fb_helper_initial_config); * either the output polling work or a work item launched from the driver's * hotplug interrupt). * - * Note that the driver must ensure that this is only called _after_ the fb has - * been fully set up, i.e. after the call to drm_fb_helper_initial_config. + * Note that drivers may call this even before calling + * drm_fb_helper_initial_config but only aftert drm_fb_helper_init. This allows + * for a race-free fbcon setup and will make sure that the fbdev emulation will + * not miss any hotplug events. * * RETURNS: * 0 on success and a non-zero error code otherwise. @@ -1624,11 +1626,8 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) struct drm_device *dev = fb_helper->dev; u32 max_width, max_height;
- if (!fb_helper->fb) - return 0; - mutex_lock(&fb_helper->dev->mode_config.mutex); - if (!drm_fb_helper_is_bound(fb_helper)) { + if (!fb_helper->fb || !drm_fb_helper_is_bound(fb_helper)) { fb_helper->delayed_hotplug = true; mutex_unlock(&fb_helper->dev->mode_config.mutex); return 0; diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index 5e583a1838f8..84b55665bd87 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -1377,9 +1377,6 @@ static int i915_load_modeset_init(struct drm_device *dev) */ intel_fbdev_initial_config(dev);
- /* Only enable hotplug handling once the fbdev is fully set up. */ - dev_priv->enable_hotplug_processing = true; - drm_kms_helper_poll_init(dev);
return 0; diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 6eb45ac7a7d5..b0955fffca98 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -521,7 +521,6 @@ static int i915_drm_freeze(struct drm_device *dev) }
intel_runtime_pm_disable_interrupts(dev); - dev_priv->enable_hotplug_processing = false;
intel_suspend_gt_powersave(dev);
@@ -659,7 +658,6 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings) * notifications. * */ intel_hpd_init(dev); - dev_priv->enable_hotplug_processing = true; /* Config may have changed between suspend and resume */ drm_helper_hpd_irq_event(dev); } diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 8cea59649ef2..df6a98cd702f 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1404,7 +1404,6 @@ struct drm_i915_private { u32 pipestat_irq_mask[I915_MAX_PIPES];
struct work_struct hotplug_work; - bool enable_hotplug_processing; struct { unsigned long hpd_last_jiffies; int hpd_cnt; diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 1c1ec22bc7ef..c0d7674c45cd 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1109,10 +1109,6 @@ static void i915_hotplug_work_func(struct work_struct *work) bool changed = false; u32 hpd_event_bits;
- /* HPD irq before everything is fully set up. */ - if (!dev_priv->enable_hotplug_processing) - return; - mutex_lock(&mode_config->mutex); DRM_DEBUG_KMS("running encoder hotplug functions\n");
From: Thierry Reding treding@nvidia.com
There's no need for this to be modifiable. Make it const so that it can be put into the .rodata section.
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/armada/armada_fbdev.c | 2 +- drivers/gpu/drm/ast/ast_fb.c | 2 +- drivers/gpu/drm/bochs/bochs_fbdev.c | 2 +- drivers/gpu/drm/cirrus/cirrus_fbdev.c | 2 +- drivers/gpu/drm/drm_fb_cma_helper.c | 2 +- drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 2 +- drivers/gpu/drm/gma500/framebuffer.c | 2 +- drivers/gpu/drm/i915/intel_fbdev.c | 2 +- drivers/gpu/drm/mgag200/mgag200_fb.c | 2 +- drivers/gpu/drm/msm/msm_fbdev.c | 2 +- drivers/gpu/drm/nouveau/nouveau_fbcon.c | 2 +- drivers/gpu/drm/omapdrm/omap_fbdev.c | 2 +- drivers/gpu/drm/qxl/qxl_fb.c | 2 +- drivers/gpu/drm/radeon/radeon_fb.c | 2 +- drivers/gpu/drm/tegra/fb.c | 2 +- drivers/gpu/drm/udl/udl_fb.c | 2 +- include/drm/drm_fb_helper.h | 2 +- 17 files changed, 17 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/armada/armada_fbdev.c b/drivers/gpu/drm/armada/armada_fbdev.c index fd166f532ab9..a7c947cd9386 100644 --- a/drivers/gpu/drm/armada/armada_fbdev.c +++ b/drivers/gpu/drm/armada/armada_fbdev.c @@ -131,7 +131,7 @@ static int armada_fb_probe(struct drm_fb_helper *fbh, return ret; }
-static struct drm_fb_helper_funcs armada_fb_helper_funcs = { +static const struct drm_fb_helper_funcs armada_fb_helper_funcs = { .gamma_set = armada_drm_crtc_gamma_set, .gamma_get = armada_drm_crtc_gamma_get, .fb_probe = armada_fb_probe, diff --git a/drivers/gpu/drm/ast/ast_fb.c b/drivers/gpu/drm/ast/ast_fb.c index a28640f47c27..2113894e4ff8 100644 --- a/drivers/gpu/drm/ast/ast_fb.c +++ b/drivers/gpu/drm/ast/ast_fb.c @@ -287,7 +287,7 @@ static void ast_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green, *blue = ast_crtc->lut_b[regno] << 8; }
-static struct drm_fb_helper_funcs ast_fb_helper_funcs = { +static const struct drm_fb_helper_funcs ast_fb_helper_funcs = { .gamma_set = ast_fb_gamma_set, .gamma_get = ast_fb_gamma_get, .fb_probe = astfb_create, diff --git a/drivers/gpu/drm/bochs/bochs_fbdev.c b/drivers/gpu/drm/bochs/bochs_fbdev.c index 561b84474122..17e5c17f2730 100644 --- a/drivers/gpu/drm/bochs/bochs_fbdev.c +++ b/drivers/gpu/drm/bochs/bochs_fbdev.c @@ -179,7 +179,7 @@ void bochs_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green, *blue = regno; }
-static struct drm_fb_helper_funcs bochs_fb_helper_funcs = { +static const struct drm_fb_helper_funcs bochs_fb_helper_funcs = { .gamma_set = bochs_fb_gamma_set, .gamma_get = bochs_fb_gamma_get, .fb_probe = bochsfb_create, diff --git a/drivers/gpu/drm/cirrus/cirrus_fbdev.c b/drivers/gpu/drm/cirrus/cirrus_fbdev.c index 32bbba0a787b..2bd0291168e4 100644 --- a/drivers/gpu/drm/cirrus/cirrus_fbdev.c +++ b/drivers/gpu/drm/cirrus/cirrus_fbdev.c @@ -288,7 +288,7 @@ static int cirrus_fbdev_destroy(struct drm_device *dev, return 0; }
-static struct drm_fb_helper_funcs cirrus_fb_helper_funcs = { +static const struct drm_fb_helper_funcs cirrus_fb_helper_funcs = { .gamma_set = cirrus_crtc_fb_gamma_set, .gamma_get = cirrus_crtc_fb_gamma_get, .fb_probe = cirrusfb_create, diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c index f27c883be391..cb01e1606384 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -327,7 +327,7 @@ err_drm_gem_cma_free_object: return ret; }
-static struct drm_fb_helper_funcs drm_fb_cma_helper_funcs = { +static const struct drm_fb_helper_funcs drm_fb_cma_helper_funcs = { .fb_probe = drm_fbdev_cma_create, };
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c index d771b467cf0c..fc25fe75aa77 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c @@ -225,7 +225,7 @@ out: return ret; }
-static struct drm_fb_helper_funcs exynos_drm_fb_helper_funcs = { +static const struct drm_fb_helper_funcs exynos_drm_fb_helper_funcs = { .fb_probe = exynos_drm_fbdev_create, };
diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c index e7fcc148f333..76e4d777d01d 100644 --- a/drivers/gpu/drm/gma500/framebuffer.c +++ b/drivers/gpu/drm/gma500/framebuffer.c @@ -561,7 +561,7 @@ static int psbfb_probe(struct drm_fb_helper *helper, return psbfb_create(psb_fbdev, sizes); }
-static struct drm_fb_helper_funcs psb_fb_helper_funcs = { +static const struct drm_fb_helper_funcs psb_fb_helper_funcs = { .gamma_set = psbfb_gamma_set, .gamma_get = psbfb_gamma_get, .fb_probe = psbfb_probe, diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c index 226fbc7d9464..c14073094024 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -478,7 +478,7 @@ out: return true; }
-static struct drm_fb_helper_funcs intel_fb_helper_funcs = { +static const struct drm_fb_helper_funcs intel_fb_helper_funcs = { .initial_config = intel_fb_initial_config, .gamma_set = intel_crtc_fb_gamma_set, .gamma_get = intel_crtc_fb_gamma_get, diff --git a/drivers/gpu/drm/mgag200/mgag200_fb.c b/drivers/gpu/drm/mgag200/mgag200_fb.c index 13b7dd83faa9..a4319aba9180 100644 --- a/drivers/gpu/drm/mgag200/mgag200_fb.c +++ b/drivers/gpu/drm/mgag200/mgag200_fb.c @@ -272,7 +272,7 @@ static int mga_fbdev_destroy(struct drm_device *dev, return 0; }
-static struct drm_fb_helper_funcs mga_fb_helper_funcs = { +static const struct drm_fb_helper_funcs mga_fb_helper_funcs = { .gamma_set = mga_crtc_fb_gamma_set, .gamma_get = mga_crtc_fb_gamma_get, .fb_probe = mgag200fb_create, diff --git a/drivers/gpu/drm/msm/msm_fbdev.c b/drivers/gpu/drm/msm/msm_fbdev.c index a752ab83b810..c229bf6e865e 100644 --- a/drivers/gpu/drm/msm/msm_fbdev.c +++ b/drivers/gpu/drm/msm/msm_fbdev.c @@ -177,7 +177,7 @@ static void msm_crtc_fb_gamma_get(struct drm_crtc *crtc, DBG("fbdev: get gamma"); }
-static struct drm_fb_helper_funcs msm_fb_helper_funcs = { +static const struct drm_fb_helper_funcs msm_fb_helper_funcs = { .gamma_set = msm_crtc_fb_gamma_set, .gamma_get = msm_crtc_fb_gamma_get, .fb_probe = msm_fbdev_create, diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c index 64a42cfd3717..8e9c07b7fc89 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c +++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c @@ -438,7 +438,7 @@ void nouveau_fbcon_gpu_lockup(struct fb_info *info) info->flags |= FBINFO_HWACCEL_DISABLED; }
-static struct drm_fb_helper_funcs nouveau_fbcon_helper_funcs = { +static const struct drm_fb_helper_funcs nouveau_fbcon_helper_funcs = { .gamma_set = nouveau_fbcon_gamma_set, .gamma_get = nouveau_fbcon_gamma_get, .fb_probe = nouveau_fbcon_create, diff --git a/drivers/gpu/drm/omapdrm/omap_fbdev.c b/drivers/gpu/drm/omapdrm/omap_fbdev.c index 1388ca7f87e8..4cb12083eb12 100644 --- a/drivers/gpu/drm/omapdrm/omap_fbdev.c +++ b/drivers/gpu/drm/omapdrm/omap_fbdev.c @@ -281,7 +281,7 @@ fail: return ret; }
-static struct drm_fb_helper_funcs omap_fb_helper_funcs = { +static const struct drm_fb_helper_funcs omap_fb_helper_funcs = { .fb_probe = omap_fbdev_create, };
diff --git a/drivers/gpu/drm/qxl/qxl_fb.c b/drivers/gpu/drm/qxl/qxl_fb.c index f437b30ce689..cf89614c72be 100644 --- a/drivers/gpu/drm/qxl/qxl_fb.c +++ b/drivers/gpu/drm/qxl/qxl_fb.c @@ -660,7 +660,7 @@ static int qxl_fbdev_destroy(struct drm_device *dev, struct qxl_fbdev *qfbdev) return 0; }
-static struct drm_fb_helper_funcs qxl_fb_helper_funcs = { +static const struct drm_fb_helper_funcs qxl_fb_helper_funcs = { .fb_probe = qxl_fb_find_or_create_single, };
diff --git a/drivers/gpu/drm/radeon/radeon_fb.c b/drivers/gpu/drm/radeon/radeon_fb.c index 665ced3b7313..ad97afdbc4c7 100644 --- a/drivers/gpu/drm/radeon/radeon_fb.c +++ b/drivers/gpu/drm/radeon/radeon_fb.c @@ -331,7 +331,7 @@ static int radeon_fbdev_destroy(struct drm_device *dev, struct radeon_fbdev *rfb return 0; }
-static struct drm_fb_helper_funcs radeon_fb_helper_funcs = { +static const struct drm_fb_helper_funcs radeon_fb_helper_funcs = { .gamma_set = radeon_crtc_fb_gamma_set, .gamma_get = radeon_crtc_fb_gamma_get, .fb_probe = radeonfb_create, diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c index 9798a7080322..f7cf47bf0afb 100644 --- a/drivers/gpu/drm/tegra/fb.c +++ b/drivers/gpu/drm/tegra/fb.c @@ -267,7 +267,7 @@ release: return err; }
-static struct drm_fb_helper_funcs tegra_fb_helper_funcs = { +static const struct drm_fb_helper_funcs tegra_fb_helper_funcs = { .fb_probe = tegra_fbdev_probe, };
diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c index 377176372da8..0647c8cc368b 100644 --- a/drivers/gpu/drm/udl/udl_fb.c +++ b/drivers/gpu/drm/udl/udl_fb.c @@ -550,7 +550,7 @@ out: return ret; }
-static struct drm_fb_helper_funcs udl_fb_helper_funcs = { +static const struct drm_fb_helper_funcs udl_fb_helper_funcs = { .fb_probe = udlfb_create, };
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h index 7997246d4039..a47df7ca38e8 100644 --- a/include/drm/drm_fb_helper.h +++ b/include/drm/drm_fb_helper.h @@ -87,7 +87,7 @@ struct drm_fb_helper { struct drm_fb_helper_crtc *crtc_info; int connector_count; struct drm_fb_helper_connector **connector_info; - struct drm_fb_helper_funcs *funcs; + const struct drm_fb_helper_funcs *funcs; struct fb_info *fbdev; u32 pseudo_palette[17]; struct list_head kernel_fb_list;
On Fri, Jun 27, 2014 at 05:19:23PM +0200, Thierry Reding wrote:
From: Thierry Reding treding@nvidia.com
There's no need for this to be modifiable. Make it const so that it can be put into the .rodata section.
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Thierry Reding treding@nvidia.com
Definitely a good thing. For Armada:
Acked-by: Russell King rmk+kernel@arm.linux.org.uk
From: Thierry Reding treding@nvidia.com
To implement hotplug detection in a race-free manner, drivers must call drm_kms_helper_poll_init() before hotplug events can be triggered. Such events can be triggered right after any of the encoders or connectors are initialized. At the same time, if the drm_fb_helper_hotplug_event() helper is used by a driver, then the poll helper requires some parts of the FB helper to be initialized to prevent a crash.
At the same time, drm_fb_helper_init() requires information that is not necessarily available at such an early stage (number of CRTCs and connectors), so it cannot be used yet.
Add a new helper, drm_fb_helper_prepare(), that initializes the bare minimum needed to allow drm_kms_helper_poll_init() to execute and any subsequent hotplug events to be processed properly.
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Thierry Reding treding@nvidia.com --- Changes in v3: - fix inconsistency "second" -> "third" (Daniel Vetter)
Changes in v2: - improve kernel-doc (Daniel Vetter)
drivers/gpu/drm/armada/armada_fbdev.c | 2 +- drivers/gpu/drm/ast/ast_fb.c | 4 ++- drivers/gpu/drm/bochs/bochs_fbdev.c | 3 +- drivers/gpu/drm/cirrus/cirrus_fbdev.c | 4 ++- drivers/gpu/drm/drm_fb_cma_helper.c | 3 +- drivers/gpu/drm/drm_fb_helper.c | 47 ++++++++++++++++++++++++------- drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 3 +- drivers/gpu/drm/gma500/framebuffer.c | 3 +- drivers/gpu/drm/i915/intel_fbdev.c | 3 +- drivers/gpu/drm/mgag200/mgag200_fb.c | 3 +- drivers/gpu/drm/msm/msm_fbdev.c | 2 +- drivers/gpu/drm/nouveau/nouveau_fbcon.c | 3 +- drivers/gpu/drm/omapdrm/omap_fbdev.c | 2 +- drivers/gpu/drm/qxl/qxl_fb.c | 5 +++- drivers/gpu/drm/radeon/radeon_fb.c | 4 ++- drivers/gpu/drm/tegra/fb.c | 4 +-- drivers/gpu/drm/udl/udl_fb.c | 3 +- include/drm/drm_fb_helper.h | 2 ++ 18 files changed, 72 insertions(+), 28 deletions(-)
diff --git a/drivers/gpu/drm/armada/armada_fbdev.c b/drivers/gpu/drm/armada/armada_fbdev.c index a7c947cd9386..7838e731b0de 100644 --- a/drivers/gpu/drm/armada/armada_fbdev.c +++ b/drivers/gpu/drm/armada/armada_fbdev.c @@ -149,7 +149,7 @@ int armada_fbdev_init(struct drm_device *dev)
priv->fbdev = fbh;
- fbh->funcs = &armada_fb_helper_funcs; + drm_fb_helper_prepare(dev, fbh, &armada_fb_helper_funcs);
ret = drm_fb_helper_init(dev, fbh, 1, 1); if (ret) { diff --git a/drivers/gpu/drm/ast/ast_fb.c b/drivers/gpu/drm/ast/ast_fb.c index 2113894e4ff8..cba45c774552 100644 --- a/drivers/gpu/drm/ast/ast_fb.c +++ b/drivers/gpu/drm/ast/ast_fb.c @@ -328,8 +328,10 @@ int ast_fbdev_init(struct drm_device *dev) return -ENOMEM;
ast->fbdev = afbdev; - afbdev->helper.funcs = &ast_fb_helper_funcs; spin_lock_init(&afbdev->dirty_lock); + + drm_fb_helper_prepare(dev, &afbdev->helper, &ast_fb_helper_funcs); + ret = drm_fb_helper_init(dev, &afbdev->helper, 1, 1); if (ret) { diff --git a/drivers/gpu/drm/bochs/bochs_fbdev.c b/drivers/gpu/drm/bochs/bochs_fbdev.c index 17e5c17f2730..19cf3e9413b6 100644 --- a/drivers/gpu/drm/bochs/bochs_fbdev.c +++ b/drivers/gpu/drm/bochs/bochs_fbdev.c @@ -189,7 +189,8 @@ int bochs_fbdev_init(struct bochs_device *bochs) { int ret;
- bochs->fb.helper.funcs = &bochs_fb_helper_funcs; + drm_fb_helper_prepare(bochs->dev, &bochs->fb.helper, + &bochs_fb_helper_funcs);
ret = drm_fb_helper_init(bochs->dev, &bochs->fb.helper, 1, 1); diff --git a/drivers/gpu/drm/cirrus/cirrus_fbdev.c b/drivers/gpu/drm/cirrus/cirrus_fbdev.c index 2bd0291168e4..2a135f253e29 100644 --- a/drivers/gpu/drm/cirrus/cirrus_fbdev.c +++ b/drivers/gpu/drm/cirrus/cirrus_fbdev.c @@ -306,9 +306,11 @@ int cirrus_fbdev_init(struct cirrus_device *cdev) return -ENOMEM;
cdev->mode_info.gfbdev = gfbdev; - gfbdev->helper.funcs = &cirrus_fb_helper_funcs; spin_lock_init(&gfbdev->dirty_lock);
+ drm_fb_helper_prepare(cdev->dev, &gfbdev->helper, + &cirrus_fb_helper_funcs); + ret = drm_fb_helper_init(cdev->dev, &gfbdev->helper, cdev->num_crtc, CIRRUSFB_CONN_LIMIT); if (ret) { diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c index cb01e1606384..cc0ae047ed3b 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -354,9 +354,10 @@ struct drm_fbdev_cma *drm_fbdev_cma_init(struct drm_device *dev, return ERR_PTR(-ENOMEM); }
- fbdev_cma->fb_helper.funcs = &drm_fb_cma_helper_funcs; helper = &fbdev_cma->fb_helper;
+ drm_fb_helper_prepare(dev, helper, &drm_fb_cma_helper_funcs); + ret = drm_fb_helper_init(dev, helper, num_crtc, max_conn_count); if (ret < 0) { dev_err(dev->dev, "Failed to initialize drm fb helper.\n"); diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 13a098c9af31..14aef947b3d2 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -49,10 +49,11 @@ static LIST_HEAD(kernel_fb_helper_list); * helper functions used by many drivers to implement the kernel mode setting * interfaces. * - * Initialization is done as a three-step process with drm_fb_helper_init(), - * drm_fb_helper_single_add_all_connectors() and drm_fb_helper_initial_config(). - * Drivers with fancier requirements than the default behaviour can override the - * second step with their own code. Teardown is done with drm_fb_helper_fini(). + * Initialization is done as a four-step process with drm_fb_helper_prepare(), + * drm_fb_helper_init(), drm_fb_helper_single_add_all_connectors() and + * drm_fb_helper_initial_config(). Drivers with fancier requirements than the + * default behaviour can override the third step with their own code. + * Teardown is done with drm_fb_helper_fini(). * * At runtime drivers should restore the fbdev console by calling * drm_fb_helper_restore_fbdev_mode() from their ->lastclose callback. They @@ -63,6 +64,19 @@ static LIST_HEAD(kernel_fb_helper_list); * * All other functions exported by the fb helper library can be used to * implement the fbdev driver interface by the driver. + * + * It is possible, though perhaps somewhat tricky, to implement race-free + * hotplug detection using the fbdev helpers. The drm_fb_helper_prepare() + * helper must be called first to initialize the minimum required to make + * hotplug detection work. Drivers also need to make sure to properly set up + * the dev->mode_config.funcs member. After calling drm_kms_helper_poll_init() + * it is safe to enable interrupts and start processing hotplug events. At the + * same time, drivers should initialize all modeset objects such as CRTCs, + * encoders and connectors. To finish up the fbdev helper initialization, the + * drm_fb_helper_init() function is called. To probe for all attached displays + * and set up an initial configuration using the detected hardware, drivers + * should call drm_fb_helper_single_add_all_connectors() followed by + * drm_fb_helper_initial_config(). */
/** @@ -531,6 +545,24 @@ static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper) }
/** + * drm_fb_helper_prepare - setup a drm_fb_helper structure + * @dev: DRM device + * @helper: driver-allocated fbdev helper structure to set up + * @funcs: pointer to structure of functions associate with this helper + * + * Sets up the bare minimum to make the framebuffer helper usable. This is + * useful to implement race-free initialization of the polling helpers. + */ +void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper, + const struct drm_fb_helper_funcs *funcs) +{ + INIT_LIST_HEAD(&helper->kernel_fb_list); + helper->funcs = funcs; + helper->dev = dev; +} +EXPORT_SYMBOL(drm_fb_helper_prepare); + +/** * drm_fb_helper_init - initialize a drm_fb_helper structure * @dev: drm device * @fb_helper: driver-allocated fbdev helper structure to initialize @@ -542,8 +574,7 @@ static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper) * nor register the fbdev. This is only done in drm_fb_helper_initial_config() * to allow driver writes more control over the exact init sequence. * - * Drivers must set fb_helper->funcs before calling - * drm_fb_helper_initial_config(). + * Drivers must call drm_fb_helper_prepare() before calling this function. * * RETURNS: * Zero if everything went ok, nonzero otherwise. @@ -558,10 +589,6 @@ int drm_fb_helper_init(struct drm_device *dev, if (!max_conn_count) return -EINVAL;
- fb_helper->dev = dev; - - INIT_LIST_HEAD(&fb_helper->kernel_fb_list); - fb_helper->crtc_info = kcalloc(crtc_count, sizeof(struct drm_fb_helper_crtc), GFP_KERNEL); if (!fb_helper->crtc_info) return -ENOMEM; diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c index fc25fe75aa77..32e63f60e1d1 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c @@ -266,7 +266,8 @@ int exynos_drm_fbdev_init(struct drm_device *dev) return -ENOMEM;
private->fb_helper = helper = &fbdev->drm_fb_helper; - helper->funcs = &exynos_drm_fb_helper_funcs; + + drm_fb_helper_prepare(dev, helper, &exynos_drm_fb_helper_funcs);
num_crtc = dev->mode_config.num_crtc;
diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c index 76e4d777d01d..d0dd3bea8aa5 100644 --- a/drivers/gpu/drm/gma500/framebuffer.c +++ b/drivers/gpu/drm/gma500/framebuffer.c @@ -600,7 +600,8 @@ int psb_fbdev_init(struct drm_device *dev) }
dev_priv->fbdev = fbdev; - fbdev->psb_fb_helper.funcs = &psb_fb_helper_funcs; + + drm_fb_helper_prepare(dev, &fbdev->psb_fb_helper, &psb_fb_helper_funcs);
drm_fb_helper_init(dev, &fbdev->psb_fb_helper, dev_priv->ops->crtcs, INTELFB_CONN_LIMIT); diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c index c14073094024..44e17fd781b8 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -649,7 +649,8 @@ int intel_fbdev_init(struct drm_device *dev) if (ifbdev == NULL) return -ENOMEM;
- ifbdev->helper.funcs = &intel_fb_helper_funcs; + drm_fb_helper_prepare(dev, &ifbdev->helper, &intel_fb_helper_funcs); + if (!intel_fbdev_init_bios(dev, ifbdev)) ifbdev->preferred_bpp = 32;
diff --git a/drivers/gpu/drm/mgag200/mgag200_fb.c b/drivers/gpu/drm/mgag200/mgag200_fb.c index a4319aba9180..5451dc58eff1 100644 --- a/drivers/gpu/drm/mgag200/mgag200_fb.c +++ b/drivers/gpu/drm/mgag200/mgag200_fb.c @@ -293,9 +293,10 @@ int mgag200_fbdev_init(struct mga_device *mdev) return -ENOMEM;
mdev->mfbdev = mfbdev; - mfbdev->helper.funcs = &mga_fb_helper_funcs; spin_lock_init(&mfbdev->dirty_lock);
+ drm_fb_helper_prepare(mdev->dev, &mfbdev->helper, &mga_fb_helper_funcs); + ret = drm_fb_helper_init(mdev->dev, &mfbdev->helper, mdev->num_crtc, MGAG200FB_CONN_LIMIT); if (ret) diff --git a/drivers/gpu/drm/msm/msm_fbdev.c b/drivers/gpu/drm/msm/msm_fbdev.c index c229bf6e865e..c7d6e85a7bf0 100644 --- a/drivers/gpu/drm/msm/msm_fbdev.c +++ b/drivers/gpu/drm/msm/msm_fbdev.c @@ -197,7 +197,7 @@ struct drm_fb_helper *msm_fbdev_init(struct drm_device *dev)
helper = &fbdev->base;
- helper->funcs = &msm_fb_helper_funcs; + drm_fb_helper_prepare(dev, helper, &msm_fb_helper_funcs);
ret = drm_fb_helper_init(dev, helper, priv->num_crtcs, priv->num_connectors); diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c index 8e9c07b7fc89..afe706a20f97 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c +++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c @@ -464,7 +464,8 @@ nouveau_fbcon_init(struct drm_device *dev)
fbcon->dev = dev; drm->fbcon = fbcon; - fbcon->helper.funcs = &nouveau_fbcon_helper_funcs; + + drm_fb_helper_prepare(dev, &fbcon->helper, &nouveau_fbcon_helper_funcs);
ret = drm_fb_helper_init(dev, &fbcon->helper, dev->mode_config.num_crtc, 4); diff --git a/drivers/gpu/drm/omapdrm/omap_fbdev.c b/drivers/gpu/drm/omapdrm/omap_fbdev.c index 4cb12083eb12..8436c6857cda 100644 --- a/drivers/gpu/drm/omapdrm/omap_fbdev.c +++ b/drivers/gpu/drm/omapdrm/omap_fbdev.c @@ -325,7 +325,7 @@ struct drm_fb_helper *omap_fbdev_init(struct drm_device *dev)
helper = &fbdev->base;
- helper->funcs = &omap_fb_helper_funcs; + drm_fb_helper_prepare(dev, helper, &omap_fb_helper_funcs);
ret = drm_fb_helper_init(dev, helper, priv->num_crtcs, priv->num_connectors); diff --git a/drivers/gpu/drm/qxl/qxl_fb.c b/drivers/gpu/drm/qxl/qxl_fb.c index cf89614c72be..df567888bb1e 100644 --- a/drivers/gpu/drm/qxl/qxl_fb.c +++ b/drivers/gpu/drm/qxl/qxl_fb.c @@ -676,9 +676,12 @@ int qxl_fbdev_init(struct qxl_device *qdev)
qfbdev->qdev = qdev; qdev->mode_info.qfbdev = qfbdev; - qfbdev->helper.funcs = &qxl_fb_helper_funcs; spin_lock_init(&qfbdev->delayed_ops_lock); INIT_LIST_HEAD(&qfbdev->delayed_ops); + + drm_fb_helper_prepare(qdev->ddev, &qfbdev->helper, + &qxl_fb_helper_funcs); + ret = drm_fb_helper_init(qdev->ddev, &qfbdev->helper, qxl_num_crtc /* num_crtc - QXL supports just 1 */, QXLFB_CONN_LIMIT); diff --git a/drivers/gpu/drm/radeon/radeon_fb.c b/drivers/gpu/drm/radeon/radeon_fb.c index ad97afdbc4c7..db598d712901 100644 --- a/drivers/gpu/drm/radeon/radeon_fb.c +++ b/drivers/gpu/drm/radeon/radeon_fb.c @@ -353,7 +353,9 @@ int radeon_fbdev_init(struct radeon_device *rdev)
rfbdev->rdev = rdev; rdev->mode_info.rfbdev = rfbdev; - rfbdev->helper.funcs = &radeon_fb_helper_funcs; + + drm_fb_helper_prepare(rdev->ddev, &rfbdev->helper, + &radeon_fb_helper_funcs);
ret = drm_fb_helper_init(rdev->ddev, &rfbdev->helper, rdev->num_crtc, diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c index f7cf47bf0afb..d5d53aa79ced 100644 --- a/drivers/gpu/drm/tegra/fb.c +++ b/drivers/gpu/drm/tegra/fb.c @@ -276,7 +276,6 @@ static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm, unsigned int num_crtc, unsigned int max_connectors) { - struct drm_fb_helper *helper; struct tegra_fbdev *fbdev; int err;
@@ -286,8 +285,7 @@ static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm, return ERR_PTR(-ENOMEM); }
- fbdev->base.funcs = &tegra_fb_helper_funcs; - helper = &fbdev->base; + drm_fb_helper_prepare(drm, &fbdev->base, &tegra_fb_helper_funcs);
err = drm_fb_helper_init(drm, &fbdev->base, num_crtc, max_connectors); if (err < 0) { diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c index 0647c8cc368b..d1da339843ca 100644 --- a/drivers/gpu/drm/udl/udl_fb.c +++ b/drivers/gpu/drm/udl/udl_fb.c @@ -583,7 +583,8 @@ int udl_fbdev_init(struct drm_device *dev) return -ENOMEM;
udl->fbdev = ufbdev; - ufbdev->helper.funcs = &udl_fb_helper_funcs; + + drm_fb_helper_prepare(dev, &ufbdev->helper, &udl_fb_helper_funcs);
ret = drm_fb_helper_init(dev, &ufbdev->helper, 1, 1); diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h index a47df7ca38e8..1cf587f1f927 100644 --- a/include/drm/drm_fb_helper.h +++ b/include/drm/drm_fb_helper.h @@ -97,6 +97,8 @@ struct drm_fb_helper { bool delayed_hotplug; };
+void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper, + const struct drm_fb_helper_funcs *funcs); int drm_fb_helper_init(struct drm_device *dev, struct drm_fb_helper *helper, int crtc_count, int max_conn);
From: Thierry Reding treding@nvidia.com
A race condition currently exists on Tegra, where it can happen that a monitor attached via HDMI isn't detected during the initial FB helper setup, but the hotplug event happens too early to be processed by the poll helpers because they haven't been initialized yet. This happens because on some boards the HDMI driver can control the regulator that supplies the +5V pin on the HDMI connector. Therefore depending on the timing between the initialization of the HDMI driver and the rest of DRM, it's possible that the monitor returns the hotplug signal right within the window where we would miss it.
Unfortunately, drm_kms_helper_poll_init() will wreak havoc when called before at least some parts of the FB helpers have been set up.
This commit fixes this by splitting out the minimum of initialization required to make drm_kms_helper_poll_init() work into a separate function that can be called early. It is then safe to move all of the poll helper initialization to an earlier point in time (before the HDMI output driver has a chance to enable the +5V supply). That way if the hotplug signal is returned before the initial FB helper setup, the monitor will be forcefully detected at that point, and if the hotplug signal is returned after that it will be properly handled by the poll helpers.
Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/tegra/drm.c | 8 ++++++-- drivers/gpu/drm/tegra/drm.h | 1 + drivers/gpu/drm/tegra/fb.c | 47 ++++++++++++++++++++++++++++++--------------- 3 files changed, 39 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c index 3396f9f6a9f7..fd736efd14bd 100644 --- a/drivers/gpu/drm/tegra/drm.c +++ b/drivers/gpu/drm/tegra/drm.c @@ -40,6 +40,12 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
drm_mode_config_init(drm);
+ err = tegra_drm_fb_prepare(drm); + if (err < 0) + return err; + + drm_kms_helper_poll_init(drm); + err = host1x_device_init(device); if (err < 0) return err; @@ -59,8 +65,6 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags) if (err < 0) return err;
- drm_kms_helper_poll_init(drm); - return 0; }
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h index 6b8fe9d86ed4..0d30689dff01 100644 --- a/drivers/gpu/drm/tegra/drm.h +++ b/drivers/gpu/drm/tegra/drm.h @@ -280,6 +280,7 @@ struct tegra_bo *tegra_fb_get_plane(struct drm_framebuffer *framebuffer, unsigned int index); bool tegra_fb_is_bottom_up(struct drm_framebuffer *framebuffer); bool tegra_fb_is_tiled(struct drm_framebuffer *framebuffer); +int tegra_drm_fb_prepare(struct drm_device *drm); int tegra_drm_fb_init(struct drm_device *drm); void tegra_drm_fb_exit(struct drm_device *drm); #ifdef CONFIG_DRM_TEGRA_FBDEV diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c index d5d53aa79ced..fc1528e0bda1 100644 --- a/drivers/gpu/drm/tegra/fb.c +++ b/drivers/gpu/drm/tegra/fb.c @@ -271,13 +271,9 @@ static const struct drm_fb_helper_funcs tegra_fb_helper_funcs = { .fb_probe = tegra_fbdev_probe, };
-static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm, - unsigned int preferred_bpp, - unsigned int num_crtc, - unsigned int max_connectors) +static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm) { struct tegra_fbdev *fbdev; - int err;
fbdev = kzalloc(sizeof(*fbdev), GFP_KERNEL); if (!fbdev) { @@ -287,10 +283,21 @@ static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm,
drm_fb_helper_prepare(drm, &fbdev->base, &tegra_fb_helper_funcs);
+ return fbdev; +} + +static int tegra_fbdev_init(struct tegra_fbdev *fbdev, + unsigned int preferred_bpp, + unsigned int num_crtc, + unsigned int max_connectors) +{ + struct drm_device *drm = fbdev->base.dev; + int err; + err = drm_fb_helper_init(drm, &fbdev->base, num_crtc, max_connectors); if (err < 0) { dev_err(drm->dev, "failed to initialize DRM FB helper\n"); - goto free; + return err; }
err = drm_fb_helper_single_add_all_connectors(&fbdev->base); @@ -299,21 +306,17 @@ static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm, goto fini; }
- drm_helper_disable_unused_functions(drm); - err = drm_fb_helper_initial_config(&fbdev->base, preferred_bpp); if (err < 0) { dev_err(drm->dev, "failed to set initial configuration\n"); goto fini; }
- return fbdev; + return 0;
fini: drm_fb_helper_fini(&fbdev->base); -free: - kfree(fbdev); - return ERR_PTR(err); + return err; }
static void tegra_fbdev_free(struct tegra_fbdev *fbdev) @@ -364,7 +367,7 @@ static const struct drm_mode_config_funcs tegra_drm_mode_funcs = { #endif };
-int tegra_drm_fb_init(struct drm_device *drm) +int tegra_drm_fb_prepare(struct drm_device *drm) { #ifdef CONFIG_DRM_TEGRA_FBDEV struct tegra_drm *tegra = drm->dev_private; @@ -379,8 +382,7 @@ int tegra_drm_fb_init(struct drm_device *drm) drm->mode_config.funcs = &tegra_drm_mode_funcs;
#ifdef CONFIG_DRM_TEGRA_FBDEV - tegra->fbdev = tegra_fbdev_create(drm, 32, drm->mode_config.num_crtc, - drm->mode_config.num_connector); + tegra->fbdev = tegra_fbdev_create(drm); if (IS_ERR(tegra->fbdev)) return PTR_ERR(tegra->fbdev); #endif @@ -388,6 +390,21 @@ int tegra_drm_fb_init(struct drm_device *drm) return 0; }
+int tegra_drm_fb_init(struct drm_device *drm) +{ +#ifdef CONFIG_DRM_TEGRA_FBDEV + struct tegra_drm *tegra = drm->dev_private; + int err; + + err = tegra_fbdev_init(tegra->fbdev, 32, drm->mode_config.num_crtc, + drm->mode_config.num_connector); + if (err < 0) + return err; +#endif + + return 0; +} + void tegra_drm_fb_exit(struct drm_device *drm) { #ifdef CONFIG_DRM_TEGRA_FBDEV
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