> -----Original Message-----
> From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Ville
> Syrjala
> Sent: Wednesday, March 20, 2024 9:34 PM
> To: intel-gfx@lists.freedesktop.org
> Subject: [PATCH 3/6] drm/i915: Allow the initial async flip to change modifier
>
> From: Ville Syrjälä <ville.syrj...@linux.intel.com>
>
> With Xorg+modesetting on skl+ we see the following behaviour:
> 1. root pixmap is X-tiled
> 2. client submitted buffers can be Y-tiled (w/ 'Option "dmabuf_capable"') 3.
> we try to switch from the X-tiled buffer to the Y-tiled buffer
> using an async flip (when vsync is disabled).
> 4. the async flip will be rejected by i915 due to the modifier change
>
> Relax the rules a bit by turning the first async flip into a sync flip so
> that we
> can change the modifier if necessary. Note that we already convert the first
> async flip into a sync flip on adl+ in order to reprogram the watermarks.
>
> Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> ---
LGTM.
Reviewed-by: Vandita Kulkarni <vandita.kulka...@intel.com>
> .../gpu/drm/i915/display/intel_atomic_plane.c | 16 +++++++++++++---
> drivers/gpu/drm/i915/display/intel_display.c | 7 +++++++
> 2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> index 76d77d5a0409..769010d0ebc4 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> @@ -429,10 +429,20 @@ static bool intel_plane_do_async_flip(struct
> intel_plane *plane,
> * In platforms after DISPLAY13, we might need to override
> * first async flip in order to change watermark levels
> * as part of optimization.
> - * So for those, we are checking if this is a first async flip.
> - * For platforms earlier than DISPLAY13 we always do async flip.
> + *
> + * And let's do this for all skl+ so that we can eg. change the
> + * modifier as well.
> + *
> + * TODO: For older platforms there is less reason to do this as
> + * only X-tile is supported with async flips, though we could
> + * extend this so other scanout parameters (stride/etc) could
> + * be changed as well...
> + *
> + * FIXME: Platforms with need_async_flip_disable_wa==true will
> + * now end up doing two sync flips initially. Would be nice to
> + * combine those into just the one sync flip...
> */
> - return DISPLAY_VER(i915) < 13 || old_crtc_state->uapi.async_flip;
> + return DISPLAY_VER(i915) < 9 || old_crtc_state->uapi.async_flip;
> }
>
> static bool i9xx_must_disable_cxsr(const struct intel_crtc_state
> *new_crtc_state, diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> b/drivers/gpu/drm/i915/display/intel_display.c
> index d366a103a707..dbcda79cf53c 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -6061,6 +6061,13 @@ static int intel_async_flip_check_hw(struct
> intel_atomic_state *state, struct in
> return -EINVAL;
> }
>
> + /*
> + * We turn the first async flip request into a sync flip
> + * so that we can reconfigure the plane (eg. change
> modifier).
> + */
> + if (!new_crtc_state->do_async_flip)
> + continue;
> +
> if (old_plane_state->view.color_plane[0].mapping_stride !=
> new_plane_state->view.color_plane[0].mapping_stride) {
> drm_dbg_kms(&i915->drm,
> --
> 2.43.2
