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Message-ID: <ae98c379-2ddb-6b4e-0de3-2b1c68a99ee7@quicinc.com>
Date: Mon, 28 Aug 2023 16:45:17 -0700
From: Jessica Zhang <quic_jesszhan@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
Marijn Suijten <marijn.suijten@...ainline.org>,
<quic_abhinavk@...cinc.com>, <ppaalanen@...il.com>,
<contact@...rsion.fr>, <laurent.pinchart@...asonboard.com>,
<sebastian.wick@...hat.com>, <ville.syrjala@...ux.intel.com>,
<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-msm@...r.kernel.org>, <freedreno@...ts.freedesktop.org>,
<wayland-devel@...ts.freedesktop.org>
Subject: Re: [PATCH RFC v5 02/10] drm: Introduce solid fill DRM plane property
On 8/8/2023 3:57 PM, Jessica Zhang wrote:
>
>
> On 8/7/2023 6:07 PM, Dmitry Baryshkov wrote:
>>
>>
>> On 8 August 2023 00:41:07 GMT+03:00, Jessica Zhang
>> <quic_jesszhan@...cinc.com> wrote:
>>>
>>>
>>> On 8/4/2023 6:27 AM, Dmitry Baryshkov wrote:
>>>> On Fri, 28 Jul 2023 at 20:03, Jessica Zhang
>>>> <quic_jesszhan@...cinc.com> wrote:
>>>>>
>>>>> Document and add support for solid_fill property to drm_plane. In
>>>>> addition, add support for setting and getting the values for
>>>>> solid_fill.
>>>>>
>>>>> To enable solid fill planes, userspace must assign a property blob to
>>>>> the "solid_fill" plane property containing the following information:
>>>>>
>>>>> struct drm_mode_solid_fill {
>>>>> u32 version;
>>>>> u32 r, g, b;
>>>>> };
>>>>>
>>>>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
>>>>> ---
>>>>> drivers/gpu/drm/drm_atomic_state_helper.c | 9 +++++
>>>>> drivers/gpu/drm/drm_atomic_uapi.c | 55
>>>>> +++++++++++++++++++++++++++++++
>>>>> drivers/gpu/drm/drm_blend.c | 30 +++++++++++++++++
>>>>> include/drm/drm_blend.h | 1 +
>>>>> include/drm/drm_plane.h | 35 ++++++++++++++++++++
>>>>> include/uapi/drm/drm_mode.h | 24 ++++++++++++++
>>>>> 6 files changed, 154 insertions(+)
>>>>>
>>>>
>>>> [skipped most of the patch]
>>>>
>>>>> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
>>>>> index 43691058d28f..53c8efa5ad7f 100644
>>>>> --- a/include/uapi/drm/drm_mode.h
>>>>> +++ b/include/uapi/drm/drm_mode.h
>>>>> @@ -259,6 +259,30 @@ struct drm_mode_modeinfo {
>>>>> char name[DRM_DISPLAY_MODE_LEN];
>>>>> };
>>>>>
>>>>> +/**
>>>>> + * struct drm_mode_solid_fill - User info for solid fill planes
>>>>> + *
>>>>> + * This is the userspace API solid fill information structure.
>>>>> + *
>>>>> + * Userspace can enable solid fill planes by assigning the plane
>>>>> "solid_fill"
>>>>> + * property to a blob containing a single drm_mode_solid_fill
>>>>> struct populated with an RGB323232
>>>>> + * color and setting the pixel source to "SOLID_FILL".
>>>>> + *
>>>>> + * For information on the plane property, see
>>>>> drm_plane_create_solid_fill_property()
>>>>> + *
>>>>> + * @version: Version of the blob. Currently, there is only support
>>>>> for version == 1
>>>>> + * @r: Red color value of single pixel
>>>>> + * @g: Green color value of single pixel
>>>>> + * @b: Blue color value of single pixel
>>>>> + */
>>>>> +struct drm_mode_solid_fill {
>>>>> + __u32 version;
>>>>> + __u32 r;
>>>>> + __u32 g;
>>>>> + __u32 b;
>>>>
>>>> Another thought about the drm_mode_solid_fill uABI. I still think we
>>>> should add alpha here. The reason is the following:
>>>>
>>>> It is true that we have drm_plane_state::alpha and the plane's
>>>> "alpha" property. However it is documented as "the plane-wide opacity
>>>> [...] It can be combined with pixel alpha. The pixel values in the
>>>> framebuffers are expected to not be pre-multiplied by the global alpha
>>>> associated to the plane.".
>>>>
>>>> I can imagine a use case, when a user might want to enable plane-wide
>>>> opacity, set "pixel blend mode" to "Coverage" and then switch between
>>>> partially opaque framebuffer and partially opaque solid-fill without
>>>> touching the plane's alpha value.
>>>
>>> Hi Dmitry,
>>>
>>> I don't really agree that adding a solid fill alpha would be a good
>>> idea. Since the intent behind solid fill is to have a single color
>>> for the entire plane, I think it makes more sense to have solid fill
>>> rely on the global plane alpha.
>>>
>>> As stated in earlier discussions, I think having both a
>>> solid_fill.alpha and a plane_state.alpha would be redundant and serve
>>> to confuse the user as to which one to set.
>>
>> That depends on the blending mode: in Coverage mode one has
>> independent plane and contents alpha values. And I consider alpha
>> value to be a part of the colour in the rgba/bgra modes.
>
> Acked -- taking Sebastian's concern into consideration, I think I'll
> have "PIXEL_SOURCE_SOLID_FILL_RGB" and add a separate
> "PIXEL_SOURCE_SOLID_FILL_RGBA".
Hi Dmitry,
Since it looks like there's still some ongoing discussion with Pekka
about whether to support an RGBA solid fill source, I'll just leave a
note to add an RGBA source in the future.
Thanks,
Jessica Zhang
>
> Thanks,
>
> Jessica Zhang
>
>>
>>
>>>
>>> Thanks,
>>>
>>> Jessica Zhang
>>>
>>>>
>>>> --
>>>> With best wishes
>>>> Dmitry
>>
>> --
>> With best wishes
>> Dmitry
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