Re: [PATCH V5 2/2] drm/vkms: Add support for virtual hardware mode

On 08/01, Sumera Priyadarsini wrote:

Add a virtual hardware or vblank-less mode as a module to enable VKMS to emulate virtual hardware drivers. This means no vertical blanking events occur and pageflips are completed arbitrarily and when required for updating the frame.

Add a new drm_crtc_helper_funcs struct, vkms_virtual_crtc_helper_funcs() which holds the atomic helpers for virtual hardware mode. Rename the existing vkms_crtc_helper_funcs struct to vkms_vblank_crtc_helper_funcs which holds atomic helpers for the vblank mode. This makes the code flow clearer and testing virtual hardware mode.

Hi Sumera,

Thanks for working to enable it.

Add a function vkms_crtc_composer() which calls the helper function, vkms_composer_common() for plane composition in vblank-less mode. vkms_crtc_composer() is directly called in the atomic hook in vkms_crtc_atomic_begin().

However, some crc captures still use vblanks which causes the crc-based igt tests to crash. Currently, I am unsure about how to approach the one-shot implementation of crc reads so I am still working on that.

We've briefly discussed on irc that we could go ahead without covering crc-based tests. However, we should not introduce errors in the driver when trying to set crc source. For this, we need to avoid that vblank_get/put calls in vkms_set_crc_source (vkms_composer.c) Can you check it, please?

This patchset has been tested with the igt tests- kms_writeback, kms_atomic , kms_lease, kms_flip, kms_pipe_get_crc and preserves results except for subtests related to crc reads and skips tests that rely on vertical blanking.

The patch is based on Rodrigo Siqueira's patch(https://patchwork.freedesktop.org/patch/316851/?series=48469&rev=3) and the ensuing review.

Signed-off-by: Sumera Priyadarsini sylphrenadin@gmail.com

Changes in V5:

• Move vkms_crtc_composer() to this patch(Melissa)
• Add more clarification for "vblank-less" mode(Pekka)
• Replace kzalloc() with kvmalloc() in compose_active_planes()

to fix memory allocation error for output frame

• Fix checkpatch warnings (Melissa)

Changes in V3:

• Refactor patchset(Melissa)

Changes in V2:

• Add atomic helper functions in a separate struct for virtual hardware

mode (Daniel)

• Remove spinlock across 'vkms_output->lock' in vkms_crtc.c(Daniel)
• Add vkms_composer_common() (Daniel)

---

drivers/gpu/drm/vkms/vkms_composer.c | 21 ++++++++++-- drivers/gpu/drm/vkms/vkms_crtc.c | 51 ++++++++++++++++++++-------- drivers/gpu/drm/vkms/vkms_drv.c | 16 ++++++--- drivers/gpu/drm/vkms/vkms_drv.h | 2 ++ 4 files changed, 69 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c index bf3d576db225..2988d5b49eb6 100644 --- a/drivers/gpu/drm/vkms/vkms_composer.c +++ b/drivers/gpu/drm/vkms/vkms_composer.c @@ -176,11 +176,12 @@ static int compose_active_planes(void **vaddr_out, { struct drm_framebuffer *fb = &primary_composer->fb; struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);

• const void *vaddr; int i;

  if (!*vaddr_out) {

• *vaddr_out = kzalloc(gem_obj->size, GFP_KERNEL);
  

• *vaddr_out = kvmalloc(gem_obj->size, GFP_KERNEL);
  

Is this change necessary to enable vblank-less mode? Or is it treating another problem?

if (!*vaddr_out) {
	DRM_ERROR("Cannot allocate memory for output frame.");
	return -ENOMEM;

@@ -229,7 +230,7 @@ int vkms_composer_common(struct vkms_crtc_state *crtc_state,

if (ret) { if ((ret == -EINVAL || ret == -ENOMEM) && !wb_pending)

• 	kfree(vaddr_out);
  

• 	kvfree(vaddr_out);
  

  return ret; }

@@ -241,7 +242,7 @@ int vkms_composer_common(struct vkms_crtc_state *crtc_state, crtc_state->wb_pending = false; spin_unlock_irq(&out->composer_lock); } else {

• kfree(vaddr_out);
  

• kvfree(vaddr_out);
  

  }

  return 0;

@@ -295,6 +296,20 @@ void vkms_composer_worker(struct work_struct *work) drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); }

+void vkms_crtc_composer(struct vkms_crtc_state *crtc_state) +{

• struct drm_crtc *crtc = crtc_state->base.crtc;
• struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
• u32 crc32 = 0;
• int ret;
• ret = vkms_composer_common(crtc_state, out, crtc_state->wb_pending, &crc32);
• if (ret == -EINVAL)

• return;
  

• drm_crtc_add_crc_entry(crtc, true, 0, &crc32);

+}

static const char * const pipe_crc_sources[] = {"auto"};

const char *const *vkms_get_crc_sources(struct drm_crtc *crtc, diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 57bbd32e9beb..8477b33c4d09 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -222,20 +222,20 @@ static int vkms_crtc_atomic_check(struct drm_crtc *crtc, return 0; }

-static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,

• 		    struct drm_atomic_state *state)
  

+static void vkms_vblank_crtc_atomic_enable(struct drm_crtc *crtc,

• 			   struct drm_atomic_state *state)
  

{ drm_crtc_vblank_on(crtc); }

-static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,

• 		     struct drm_atomic_state *state)
  

+static void vkms_vblank_crtc_atomic_disable(struct drm_crtc *crtc,

• 			    struct drm_atomic_state *state)
  

{ drm_crtc_vblank_off(crtc); }

-static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,

• 		   struct drm_atomic_state *state)
  

+static void vkms_vblank_crtc_atomic_begin(struct drm_crtc *crtc,

• 			  struct drm_atomic_state *state)
  

{ struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);

@@ -245,8 +245,8 @@ static void vkms_crtc_atomic_begin(struct drm_crtc *crtc, spin_lock_irq(&vkms_output->lock); }

-static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,

• 		   struct drm_atomic_state *state)
  

+static void vkms_vblank_crtc_atomic_flush(struct drm_crtc *crtc,

• 			  struct drm_atomic_state *state)
  

{ struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);

@@ -268,18 +268,38 @@ static void vkms_crtc_atomic_flush(struct drm_crtc *crtc, spin_unlock_irq(&vkms_output->lock); }

-static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = { +/*

• • Crtc functions for virtual hardware/vblankless mode
• */

+static void vkms_virtual_crtc_atomic_flush(struct drm_crtc *crtc,

• 			   struct drm_atomic_state *state)
  

+{

• struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
• struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(crtc->state);
• vkms_crtc_composer(vkms_state);
• vkms_output->composer_state = to_vkms_crtc_state(crtc->state);

+}

+static const struct drm_crtc_helper_funcs vkms_vblank_crtc_helper_funcs = { .atomic_check = vkms_crtc_atomic_check,

• .atomic_begin = vkms_crtc_atomic_begin,
• .atomic_flush = vkms_crtc_atomic_flush,
• .atomic_enable = vkms_crtc_atomic_enable,
• .atomic_disable = vkms_crtc_atomic_disable,

• .atomic_begin = vkms_vblank_crtc_atomic_begin,
• .atomic_flush = vkms_vblank_crtc_atomic_flush,
• .atomic_enable = vkms_vblank_crtc_atomic_enable,
• .atomic_disable = vkms_vblank_crtc_atomic_disable,

+};

+static const struct drm_crtc_helper_funcs vkms_virtual_crtc_helper_funcs = {

• .atomic_check = vkms_crtc_atomic_check,
• .atomic_flush = vkms_virtual_crtc_atomic_flush,

};

int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, struct drm_plane *primary, struct drm_plane *cursor) { struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);

• struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev); int ret;

  ret = drm_crtc_init_with_planes(dev, crtc, primary, cursor,

@@ -289,7 +309,10 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, return ret; }

• drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);

• if (vkmsdev->config->virtual_hw)

• drm_crtc_helper_add(crtc, &vkms_virtual_crtc_helper_funcs);
  

• else

• drm_crtc_helper_add(crtc, &vkms_vblank_crtc_helper_funcs);
  
  

  spin_lock_init(&vkms_out->lock); spin_lock_init(&vkms_out->composer_lock);

diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c index 0ffe5f0e33f7..ee78f5eef653 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.c +++ b/drivers/gpu/drm/vkms/vkms_drv.c @@ -51,6 +51,10 @@ static bool enable_overlay; module_param_named(enable_overlay, enable_overlay, bool, 0444); MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");

+static bool enable_virtual_hw; +module_param_named(enable_virtual_hw, enable_virtual_hw, bool, 0444); +MODULE_PARM_DESC(enable_virtual_hw, "Enable/Disable virtual hardware mode(vblank-less mode)");

DEFINE_DRM_GEM_FOPS(vkms_driver_fops);

static void vkms_release(struct drm_device *dev) @@ -98,6 +102,7 @@ static int vkms_config_show(struct seq_file *m, void *data) seq_printf(m, "writeback=%d\n", vkmsdev->config->writeback); seq_printf(m, "cursor=%d\n", vkmsdev->config->cursor); seq_printf(m, "overlay=%d\n", vkmsdev->config->overlay);

• seq_printf(m, "virtual_hw=%d\n", vkmsdev->config->virtual_hw);

  return 0;

} @@ -191,10 +196,12 @@ static int vkms_create(struct vkms_config *config) goto out_devres; }

• ret = drm_vblank_init(&vkms_device->drm, 1);
• if (ret) {

• DRM_ERROR("Failed to vblank\n");
  

• goto out_devres;
  

• if (!vkms_device->config->virtual_hw) {

• ret = drm_vblank_init(&vkms_device->drm, 1);
  

• if (ret) {
  

• 	DRM_ERROR("Failed to vblank\n");
  

• 	goto out_devres;
  

• }
  

  }

  ret = vkms_modeset_init(vkms_device);

@@ -229,6 +236,7 @@ static int __init vkms_init(void) config->cursor = enable_cursor; config->writeback = enable_writeback; config->overlay = enable_overlay;

• config->virtual_hw = enable_virtual_hw;

  return vkms_create(config);

} diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h index 01beba424f18..770594e07f0e 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -92,6 +92,7 @@ struct vkms_config { bool writeback; bool cursor; bool overlay;

• bool virtual_hw; /* only set when instantiated */ struct vkms_device *dev;

}; @@ -136,6 +137,7 @@ int vkms_composer_common(struct vkms_crtc_state *crtc_state, struct vkms_output bool wb_pending, uint32_t *crcs); void vkms_composer_worker(struct work_struct *work); void vkms_set_composer(struct vkms_output *out, bool enabled); +void vkms_crtc_composer(struct vkms_crtc_state *crtc_state);

/* Writeback */ int vkms_enable_writeback_connector(struct vkms_device *vkmsdev); -- 2.31.1