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

[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.

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)?

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;
> > > > >    }