On Thu, Aug 29, 2024 at 01:48:34PM -0700, Jessica Zhang wrote:
> If the clone mode enabled status is changing, a modeset needs to happen
> so that the resources can be reassigned
>
> Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index 1b0cc899e8c1..99eaaca405a4 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -1306,6 +1306,8 @@ static int dpu_crtc_atomic_check(struct drm_crtc *crtc,
> int rc = 0;
>
> bool needs_dirtyfb = dpu_crtc_needs_dirtyfb(crtc_state);
> + bool clone_mode_requested = drm_crtc_in_clone_mode(crtc->state);
> + bool clone_mode_enabled = drm_crtc_in_clone_mode(crtc_state);
>
> /* there might be cases where encoder needs a modeset too */
> drm_for_each_encoder_mask(drm_enc, crtc->dev, crtc_state->encoder_mask) {
> @@ -1313,6 +1315,10 @@ static int dpu_crtc_atomic_check(struct drm_crtc *crtc,
> crtc_state->mode_changed = true;
> }
>
> + if ((clone_mode_requested && !clone_mode_enabled) ||
> + (!clone_mode_requested && clone_mode_enabled))
> + crtc_state->mode_changed = true;
So two things, and kinda about the overall patch series:
- msm is confused about crtc_state->mode_changed, e.g. it sets it if
crtc_state->active_changed, which is wrong. Or msm dpu code doesn't use
drm_atomic_crtc_needs_modeset() correctly.
- changing crtc_state->mode_changed from your crtc or plane callbacks
means you cannot use drm_atomic_helper_check directly, but need to roll
your own that calls drm_atomic_helper_check_modesets again as needed.
See the kerneldoc comment for drm_atomic_helper_check_modesets()
- the same holds if you set mode_changed from your encoder or bridge
functions, but I think this doesn't apply here for this patch.
I think it'd be really good to
- review existing kerneldoc and please submit patches where it's not clear
or detailed enough
- add checks to the atomic helper code to catch this. I think the best way
would be to check if drm_atomic_crtc_needs_modeset() changes outside of
areas where the helper code allows it already (essentially connector
functions setting ->connectors_changed), and set a new
drm_atomic_state->dirty_needs_modeset. Which
drm_atomic_helper_check_modeset would clear, and which would result in a
WARN_ON in drm_atomic_check if it's not yet cleared when the driver
returns with success.
Otherwise there's just no way I think to make sure drivers get this
right.
Can I please sign you up for these patches?
Thanks, Sima
> +
> if (drm_atomic_crtc_needs_modeset(crtc_state)) {
> rc = dpu_crtc_assign_resources(crtc, crtc_state);
> if (rc < 0)
>
> --
> 2.34.1
>
--
Simona Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
