[PATCH 0/2] drm: Fix atomic helper dirtyfb stalls

[PATCH 0/2] drm: Fix atomic helper dirtyfb stalls

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Someone on IRC once asked an innocent enough sounding question:  Why
with xf86-video-modesetting is es2gears limited at 120fps.

So I broke out the perfetto tracing mesa MR and took a look.  It turns
out the problem was drm_atomic_helper_dirtyfb(), which would end up
waiting for vblank.. es2gears would rapidly push two frames to Xorg,
which would blit them to screen and in idle hook (I assume) call the
DIRTYFB ioctl.  Which in turn would do an atomic update to flush the
dirty rects, which would stall until the next vblank.  And then the
whole process would repeat.

But this is a bit silly, we only need dirtyfb for command mode DSI
panels.  So lets just skip it otherwise.

Rob Clark (2):
  drm: Fix dirtyfb stalls
  drm/msm/dpu: Wire up needs_dirtyfb

 drivers/gpu/drm/drm_damage_helper.c      |  8 ++++++++
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 14 ++++++++++++++
 include/drm/drm_modeset_helper_vtables.h | 14 ++++++++++++++
 3 files changed, 36 insertions(+)

-- 
2.30.2

[PATCH 2/2] drm/msm/dpu: Wire up needs_dirtyfb

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 5a74f93e29da..868ee6136438 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -143,6 +143,19 @@ static bool dpu_crtc_get_scanout_position(struct drm_crtc *crtc,
 	return true;
 }
 
+static bool dpu_crtc_needs_dirtyfb(struct drm_crtc *crtc)
+{
+	struct drm_encoder *encoder;
+
+	drm_for_each_encoder_mask (encoder, crtc->dev, crtc->state->encoder_mask) {
+		if (dpu_encoder_get_intf_mode(encoder) == INTF_MODE_CMD) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
 		struct dpu_plane_state *pstate, struct dpu_format *format)
 {
@@ -1343,6 +1356,7 @@ static const struct drm_crtc_helper_funcs dpu_crtc_helper_funcs = {
 	.atomic_begin = dpu_crtc_atomic_begin,
 	.atomic_flush = dpu_crtc_atomic_flush,
 	.get_scanout_position = dpu_crtc_get_scanout_position,
+	.needs_dirtyfb = dpu_crtc_needs_dirtyfb,
 };
 
 /* initialize crtc */
-- 
2.30.2

Tested

[houdek.ryan]

I have tested this on my end and it resolves the 120hz problem.

Tested-By: Ryan Houdek <Houdek.Ryan@fex-emu.org>

Re: [PATCH 2/2] drm/msm/dpu: Wire up needs_dirtyfb

[Rob Clark]

On Sat, May 8, 2021 at 12:53 PM Rob Clark <robdclark@gmail.com> wrote:
>
> From: Rob Clark <robdclark@chromium.org>
>
> Signed-off-by: Rob Clark <robdclark@chromium.org>

From Ryan (sending this for him because mailing list workflow is lame):

I have tested this on my end and it resolves the 120hz problem.

Tested-By: Ryan Houdek <Houdek.Ryan@fex-emu.org>

> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index 5a74f93e29da..868ee6136438 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -143,6 +143,19 @@ static bool dpu_crtc_get_scanout_position(struct drm_crtc *crtc,
>         return true;
>  }
>
> +static bool dpu_crtc_needs_dirtyfb(struct drm_crtc *crtc)
> +{
> +       struct drm_encoder *encoder;
> +
> +       drm_for_each_encoder_mask (encoder, crtc->dev, crtc->state->encoder_mask) {
> +               if (dpu_encoder_get_intf_mode(encoder) == INTF_MODE_CMD) {
> +                       return true;
> +               }
> +       }
> +
> +       return false;
> +}
> +
>  static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
>                 struct dpu_plane_state *pstate, struct dpu_format *format)
>  {
> @@ -1343,6 +1356,7 @@ static const struct drm_crtc_helper_funcs dpu_crtc_helper_funcs = {
>         .atomic_begin = dpu_crtc_atomic_begin,
>         .atomic_flush = dpu_crtc_atomic_flush,
>         .get_scanout_position = dpu_crtc_get_scanout_position,
> +       .needs_dirtyfb = dpu_crtc_needs_dirtyfb,
>  };
>
>  /* initialize crtc */
> --
> 2.30.2
>

Re: Tested

[Alex Deucher]

Sorry, what patch are you referring to?

Alex

On Mon, May 10, 2021 at 4:04 AM <houdek.ryan@fex-emu.org> wrote:
>
> I have tested this on my end and it resolves the 120hz problem.
>
> Tested-By: Ryan Houdek <Houdek.Ryan@fex-emu.org>