Re: [PATCH 1/2] drm/verisilicon: set blend mode for the primary plane

[Thomas Zimmermann]

Hi

Am 10.09.26 um 10:45 schrieb Icenowy Zheng:
> 在 2026-09-10四的 10:31 +0200，Thomas Zimmermann写道：
> > Hi
> >
> > Am 10.09.26 um 10:00 schrieb Icenowy Zheng:
> > > 在 2026-09-10四的 09:58 +0200，Thomas Zimmermann写道：
> > > > Hi
> > > >
> > > > Am 10.09.26 um 09:09 schrieb Icenowy Zheng:
> > > > > 在 2026-09-02三的 01:17 +0800，Icenowy Zheng写道：
> > > > > > Blend modes are now required to expose pixel formats w/
> > > > > > alpha.
> > > > > >
> > > > > > As it's the primary plane and blending is explicitly
> > > > > > disabled,
> > > > > > just
> > > > > > expose PIXEL_NONE blend mode.
> > > > > Gently ping for reviews.
> > > > What do these alpha formats do?  Are they a hardware feature?  It
> > > > looks
> > > > like they are programmable, but don't differ from XRGB at all.
> > > I think they're for consistency with overlay planes.
> > But there are no overlay planes in this driver, are there?
> >
> > What I want to get at is that it might be preferable to remove ARGB
> > entirely from the primary plane if it does not to serve a purpose.
> > But
> > if the driver can do something useful with these formats, it might be
> > worth exposing that instead.
> On DC8000 display controllers (support for them is WIP by Joey Lu)
> there seem to be no way to control the blend behavior of the primary
> plane.
>
> On DC8200 display controllers the primary plane does have a blending
> register, although it seems to be blending with pure black.

IIRC there's a background-color property for the CRTC.  So it might be 
possible to expose this as read-only property. (Not sure.)

> Maybe it's viable to just remove the ARGB formats now, and re-introduce
> them when overlays are being implemented (and only expose them for the
> overlay)?

I see. Thanks for digging through this. I've meanwhile acked the patches 
as there's at least some support in hardware.

Best regards
Thomas


> Thanks,
> Icenowy
>
> > In pl111, we now remove the ARGB foramts because the hardware does
> > not
> > handle them at all. The situation seems less clear in verisilicon.
> >
> > Best regards
> > Thomas
> >
> >
> > > Thanks,
> > > Icenowy
> > >
> > > > Best regards
> > > > Thomas
> > > >
> > > > > Thanks,
> > > > > Icenowy
> > > > >
> > > > > > Signed-off-by: Icenowy Zheng <zhengxingda@xxxxxxxxxxx>
> > > > > > ---
> > > > > >     drivers/gpu/drm/verisilicon/vs_primary_plane.c | 3 +++
> > > > > >     1 file changed, 3 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/verisilicon/vs_primary_plane.c
> > > > > > b/drivers/gpu/drm/verisilicon/vs_primary_plane.c
> > > > > > index 1f2be41ae496c..8d58682d88ef8 100644
> > > > > > --- a/drivers/gpu/drm/verisilicon/vs_primary_plane.c
> > > > > > +++ b/drivers/gpu/drm/verisilicon/vs_primary_plane.c
> > > > > > @@ -7,6 +7,7 @@
> > > > > >     
> > > > > >     #include <drm/drm_atomic.h>
> > > > > >     #include <drm/drm_atomic_helper.h>
> > > > > > +#include <drm/drm_blend.h>
> > > > > >     #include <drm/drm_crtc.h>
> > > > > >     #include <drm/drm_fourcc.h>
> > > > > >     #include <drm/drm_framebuffer.h>
> > > > > > @@ -179,5 +180,7 @@ struct drm_plane
> > > > > > *vs_primary_plane_init(struct
> > > > > > drm_device *drm_dev, struct vs_dc
> > > > > >     
> > > > > >     	drm_plane_helper_add(plane,
> > > > > > &vs_primary_plane_helper_funcs);
> > > > > >     
> > > > > > +	drm_plane_create_blend_mode_property(plane,
> > > > > > +					
> > > > > > BIT(DRM_MODE_BLEND_PIXEL_NONE));
> > > > > >     	return plane;
> > > > > >     }

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)