On 11/13/25 18:03, Klymenko, Anatoliy wrote: > [AMD Official Use Only - AMD Internal Distribution Only] > > 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; >> + >> + 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.
Do you have a datasheet (or other) reference? But in any case, DRM_MODE_BLEND_PREMULTI is mandatory even if we don't support it. See drm_plane_create_blend_mode_property for details. --Sean
