linux-kernel - Re: [Freedreno] [PATCH RFC v6 07/10] drm/atomic: Loosen FB atomic checks

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Message-ID: <6851b864-447f-453f-8b34-1fbb6e97eefe@linaro.org>
Date:   Sun, 24 Sep 2023 13:23:13 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Jessica Zhang <quic_jesszhan@...cinc.com>,
        Pekka Paalanen <ppaalanen@...il.com>
Cc:     linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        sebastian.wick@...hat.com, Thomas Zimmermann <tzimmermann@...e.de>,
        Sean Paul <sean@...rly.run>, dri-devel@...ts.freedesktop.org,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        quic_abhinavk@...cinc.com, Maxime Ripard <mripard@...nel.org>,
        linux-kernel@...r.kernel.org, Rob Clark <robdclark@...il.com>,
        laurent.pinchart@...asonboard.com, Daniel Vetter <daniel@...ll.ch>,
        contact@...rsion.fr,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        wayland-devel@...ts.freedesktop.org,
        David Airlie <airlied@...il.com>, ville.syrjala@...ux.intel.com
Subject: Re: [Freedreno] [PATCH RFC v6 07/10] drm/atomic: Loosen FB atomic
 checks

On 22/09/2023 20:49, Jessica Zhang wrote:
> 
> 
> On 8/29/2023 1:22 AM, Pekka Paalanen wrote:
>> On Mon, 28 Aug 2023 17:05:13 -0700
>> Jessica Zhang <quic_jesszhan@...cinc.com> wrote:
>>
>>> Loosen the requirements for atomic and legacy commit so that, in cases
>>> where pixel_source != FB, the commit can still go through.
>>>
>>> This includes adding framebuffer NULL checks in other areas to 
>>> account for
>>> FB being NULL when non-FB pixel sources are enabled.
>>>
>>> To disable a plane, the pixel_source must be NONE or the FB must be NULL
>>> if pixel_source == FB.
>>>
>>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
>>> ---
>>>   drivers/gpu/drm/drm_atomic.c        | 20 +++++++++++---------
>>>   drivers/gpu/drm/drm_atomic_helper.c | 36 
>>> ++++++++++++++++++++----------------
>>>   include/drm/drm_atomic_helper.h     |  4 ++--
>>>   include/drm/drm_plane.h             | 29 +++++++++++++++++++++++++++++
>>>   4 files changed, 62 insertions(+), 27 deletions(-)
>>
>> ...
>>
>>> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
>>> index a58f84b6bd5e..4c5b7bcdb25c 100644
>>> --- a/include/drm/drm_plane.h
>>> +++ b/include/drm/drm_plane.h
>>> @@ -992,6 +992,35 @@ static inline struct drm_plane 
>>> *drm_plane_find(struct drm_device *dev,
>>>   #define drm_for_each_plane(plane, dev) \
>>>       list_for_each_entry(plane, &(dev)->mode_config.plane_list, head)
>>> +/**
>>> + * drm_plane_solid_fill_enabled - Check if solid fill is enabled on 
>>> plane
>>> + * @state: plane state
>>> + *
>>> + * Returns:
>>> + * Whether the plane has been assigned a solid_fill_blob
>>> + */
>>> +static inline bool drm_plane_solid_fill_enabled(struct 
>>> drm_plane_state *state)
>>> +{
>>> +    if (!state)
>>> +        return false;
>>> +    return state->pixel_source == DRM_PLANE_PIXEL_SOURCE_SOLID_FILL 
>>> && state->solid_fill_blob;
>>> +}
>>> +
>>> +static inline bool drm_plane_has_visible_data(const struct 
>>> drm_plane_state *state)
>>> +{
>>> +    switch (state->pixel_source) {
>>> +    case DRM_PLANE_PIXEL_SOURCE_NONE:
>>> +        return false;
>>> +    case DRM_PLANE_PIXEL_SOURCE_SOLID_FILL:
>>> +        return state->solid_fill_blob != NULL;
>>
>> This reminds me, new UAPI docs did not say what the requirements are for
>> choosing solid fill pixel source. Is the atomic commit rejected if
>> pixel source is solid fill, but solid_fill property has no blob?
> 
> Hi Pekka,
> 
> Yes, if pixel_source is solid_fill and the solid_fill property blob 
> isn't set, the atomic commit should throw an error.
> 
> Will document this in the UAPI.

I don't see a corresponding error check in atomic_check() functions. 
Could you please check that there is one, as you are updating the uAPI.

> 
> Thanks,
> 
> Jessica Zhang
> 
>>
>> This should be doc'd.
>>
>>
>> Thanks,
>> pq
>>
>>> +    case DRM_PLANE_PIXEL_SOURCE_FB:
>>> +    default:
>>> +        WARN_ON(state->pixel_source != DRM_PLANE_PIXEL_SOURCE_FB);
>>> +    }
>>> +
>>> +    return state->fb != NULL;
>>> +}
>>> +
>>>   bool drm_any_plane_has_format(struct drm_device *dev,
>>>                     u32 format, u64 modifier);
>>>
>>

-- 
With best wishes
Dmitry