On 11/13/25 18:59, Klymenko, Anatoliy wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
>
>> -----Original Message-----
>> From: Klymenko, Anatoliy
>> Sent: Thursday, November 13, 2025 3:04 PM
>> To: 'Sean Anderson' <[email protected]>; Laurent Pinchart
>> <[email protected]>; Tomi Valkeinen
>> <[email protected]>; [email protected]
>> Cc: [email protected]; Mike Looijmans <[email protected]>;
>> David Airlie <[email protected]>; Thomas Zimmermann
>> <[email protected]>; Maarten Lankhorst
>> <[email protected]>; Maxime Ripard <[email protected]>;
>> [email protected]; Simona Vetter <[email protected]>; Simek,
>> Michal <[email protected]>
>> Subject: RE: [PATCH 3/3] drm: zynqmp: Add blend mode property to graphics
>> plane
>>
>> Hi Sean,
>>
>> Thank you for the patch.
>>
>> > -----Original Message-----
>> > From: Sean Anderson <[email protected]>
>> > Sent: Thursday, November 13, 2025 12:37 PM
>> > To: Laurent Pinchart <[email protected]>; Tomi Valkeinen
>> > <[email protected]>; [email protected]
>> > Cc: [email protected]; Mike Looijmans <[email protected]>;
>> > David Airlie <[email protected]>; Thomas Zimmermann
>> > <[email protected]>; Maarten Lankhorst
>> > <[email protected]>; Klymenko, Anatoliy
>> > <[email protected]>; Maxime Ripard <[email protected]>;
>> linux-
>> > [email protected]; Simona Vetter <[email protected]>; Simek,
>> > Michal <[email protected]>; Sean Anderson
>> > <[email protected]>
>> > Subject: [PATCH 3/3] drm: zynqmp: Add blend mode property to graphics
>> plane
>> >
>> > Caution: This message originated from an External Source. Use proper
>> caution
>> > when opening attachments, clicking links, or responding.
>> >
>> >
>> > When global alpha is enabled, per-pixel alpha is ignored. Allow
>> > userspace to explicitly specify whether to use per-pixel alpha by
>> > exposing it through the blend mode property. I'm not sure whether the
>> > per-pixel alpha is pre-multiplied or not [1], but apparently it *must* be
>> > pre-multiplied so I guess we have to advertise it.
>> >
>> > [1] All we get is "The alpha value available with the graphics stream
>> > will define the transparency of the graphics."
>> >
>> > Signed-off-by: Sean Anderson <[email protected]>
>> > ---
>> >
>> > drivers/gpu/drm/xlnx/zynqmp_kms.c | 24 ++++++++++++++++++++++--
>> > 1 file changed, 22 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/xlnx/zynqmp_kms.c
>> > b/drivers/gpu/drm/xlnx/zynqmp_kms.c
>> > index 456ada9ac003..fa1cfc16db36 100644
>> > --- a/drivers/gpu/drm/xlnx/zynqmp_kms.c
>> > +++ b/drivers/gpu/drm/xlnx/zynqmp_kms.c
>> > @@ -61,6 +61,13 @@ static int zynqmp_dpsub_plane_atomic_check(struct
>> > drm_plane *plane,
>> > if (!new_plane_state->crtc)
>> > return 0;
>> >
>> > + if (new_plane_state->pixel_blend_mode !=
>> > DRM_MODE_BLEND_PIXEL_NONE &&
>> > + new_plane_state->alpha >> 8 != 0xff) {
>> > + drm_dbg_kms(plane->dev,
>> > + "Plane alpha must be 1.0 when using pixel
>> > alpha\n");
>> > + return -EINVAL;
>> > + }
>> > +
>> > crtc_state = drm_atomic_get_crtc_state(state,
>> > new_plane_state->crtc);
>> > if (IS_ERR(crtc_state))
>> > return PTR_ERR(crtc_state);
>> > @@ -117,9 +124,13 @@ static void
>> > zynqmp_dpsub_plane_atomic_update(struct drm_plane *plane,
>> >
>> > zynqmp_disp_layer_update(layer, new_state);
>> >
>> > - if (plane->index == ZYNQMP_DPSUB_LAYER_GFX)
>> > - zynqmp_disp_blend_set_global_alpha(dpsub->disp, true,
>> > + if (plane->index == ZYNQMP_DPSUB_LAYER_GFX) {
>> > + bool blend = plane->state->pixel_blend_mode ==
>> > + DRM_MODE_BLEND_PIXEL_NONE;
>
> I would suggest adding
> || !plane->state->fb->format->has_alpha;
> pixel_blend_mode doesn't make a lot of sense for non-alpha formats but may
> have a negative effect on Mike's fix
> https://lore.kernel.org/dri-devel/[email protected]/
> if user isn't careful enough around this property.
I don't believe that patch should be applied.
--Sean
>> > +
>> > + zynqmp_disp_blend_set_global_alpha(dpsub->disp, blend,
>> > plane->state->alpha >>
>> > 8);
>> > + }
>> >
>> > /*
>> > * Unconditionally enable the layer, as it may have been disabled
>> > @@ -179,9 +190,18 @@ static int zynqmp_dpsub_create_planes(struct
>> > zynqmp_dpsub *dpsub)
>> > return ret;
>> >
>> > if (i == ZYNQMP_DPSUB_LAYER_GFX) {
>> > + unsigned int blend_modes =
>> > + BIT(DRM_MODE_BLEND_PIXEL_NONE) |
>> > + BIT(DRM_MODE_BLEND_PREMULTI);
>>
>> | BIT(DRM_MODE_BLEND_COVERAGE) - this is what implemented in the
>> hardware.
>>
>> > +
>> > ret = drm_plane_create_alpha_property(plane);
>> > if (ret)
>> > return ret;
>> > +
>> > + ret = drm_plane_create_blend_mode_property(plane,
>> > +
>> > blend_modes);
>> > + if (ret)
>> > + return ret;
>> > }
>> > }
>> >
>> > --
>> > 2.35.1.1320.gc452695387.dirty
>>
>> Thank you,
>> Anatoliy
>
> Thank you,
> Anatoliy
>
