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);