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

[Thomas Zimmermann <tzimmermann@suse.de>]

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@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;
>>>>>>     }

-- 
--
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)