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

[Icenowy Zheng <zhengxingda@iscas.ac.cn>]

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.

The device has overlay planes, but they're currently not supported.

The manual for MA35D1 does list formats with alpha for
DcregFrameBufferConfig0 register, and the hardware can properly handle
these format values (by ignoring the A bits).

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@iscas.ac.cn>
> > > > > ---
> > > > >    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;
> > > > >    }