Re: [RFC PATCH v3 1/3] drm: Introduce solid fill property for drm plane

[Harry Wentland <harry.wentland@amd.com>]

On 1/18/23 17:53, Jessica Zhang wrote:
> 
> 
> On 1/18/2023 10:57 AM, Harry Wentland wrote:
>> On 1/4/23 18:40, Jessica Zhang wrote:
>>> Add support for solid_fill property to drm_plane. In addition, add
>>> support for setting and getting the values for solid_fill.
>>>
>>> solid_fill holds data for supporting solid fill planes. The property
>>> accepts an RGB323232 value and the driver data is formatted as such:
>>>
>>> struct drm_solid_fill {
>>>     u32 r;
>>>     u32 g;
>>>     u32 b;
>>> };
>>
>> Rather than special-casing this would it make sense to define this
>> as a single pixel of a FOURCC property?
>>
>> I.e., something like this:
>>
>> struct drm_solid_fill_info {
>>     u32 format; /* FOURCC value */
>>     u64 value; /* FOURCC pixel value */
>> }
>>
>> That removes some ambiguity how the value should be interpreted, i.e.,
>> it can be interpreted like a single pixel of the specified FOURCC format.
>>
>> It might also make sense to let drivers advertise the supported
>> FOURCC formats for solid_fill planes.
> 
> Hi Harry,
> 
> The initial v1 of this RFC had support for taking in a format and such, but it was decided that just supporting RGB323232 would work too.
> 
> Here's the original thread discussing it [1], but to summarize, the work needed to convert the solid fill color to RGB is trivial (as it's just a single pixel of data). In addition, supporting various formats for solid_fill would add complexity as we'd have to communicate which formats are supported.
> 
> [1] https://lists.freedesktop.org/archives/dri-devel/2022-November/379148.html
> 

Make sense, and thanks for summarizing.

The only comment I would have left then, is that maybe it'd be good to add
an alpha value. I think it was suggested by someone else as well.

>>
>> Is there an implementation for this in a corresponding canonical
>> upstream userspace project, to satisfy [1]? If not, what is the plan
>> for this? If so, please point to the corresponding patches.
> 
> The use case we're trying to support here is the Android HWC SOLID_FILL hint [1], though it can also be used to address the Wayland single pixel FB protocol [2]. I'm also planning to add an IGT test to show an example of end to end usage.
> 
> [1] https://android.googlesource.com/platform/hardware/interfaces/+/refs/heads/master/graphics/composer/aidl/android/hardware/graphics/composer3/Composition.aidl#52
> 
> [2] https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/104
> 

Makes sense.

Harry

> Thanks,
> 
> Jessica Zhang
> 
>>
>> [1] https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements
>>
>> Harry
>>
>>>
>>> To enable solid fill planes, userspace must assigned solid_fill to a
>>> property blob containing the following information:
>>>
>>> struct drm_solid_fill_info {
>>>     u8 version;
>>>     u32 r, g, b;
>>> };
>>>
>>> Changes in V2:
>>> - Changed solid_fill property to a property blob (Simon, Dmitry)
>>> - Added drm_solid_fill struct (Simon)
>>> - Added drm_solid_fill_info struct (Simon)
>>>
>>> Changes in V3:
>>> - Corrected typo in drm_solid_fill struct documentation
>>>
>>> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
>>> ---
>>>   drivers/gpu/drm/drm_atomic_state_helper.c |  9 ++++
>>>   drivers/gpu/drm/drm_atomic_uapi.c         | 59 +++++++++++++++++++++++
>>>   drivers/gpu/drm/drm_blend.c               | 17 +++++++
>>>   include/drm/drm_blend.h                   |  1 +
>>>   include/drm/drm_plane.h                   | 43 +++++++++++++++++
>>>   5 files changed, 129 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c
>>> index dfb57217253b..c96fd1f2ad99 100644
>>> --- a/drivers/gpu/drm/drm_atomic_state_helper.c
>>> +++ b/drivers/gpu/drm/drm_atomic_state_helper.c
>>> @@ -253,6 +253,11 @@ void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,
>>>       plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
>>>       plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
>>>   +    if (plane_state->solid_fill_blob) {
>>> +        drm_property_blob_put(plane_state->solid_fill_blob);
>>> +        plane_state->solid_fill_blob = NULL;
>>> +    }
>>> +
>>>       if (plane->color_encoding_property) {
>>>           if (!drm_object_property_get_default_value(&plane->base,
>>>                                  plane->color_encoding_property,
>>> @@ -335,6 +340,9 @@ void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
>>>       if (state->fb)
>>>           drm_framebuffer_get(state->fb);
>>>   +    if (state->solid_fill_blob)
>>> +        drm_property_blob_get(state->solid_fill_blob);
>>> +
>>>       state->fence = NULL;
>>>       state->commit = NULL;
>>>       state->fb_damage_clips = NULL;
>>> @@ -384,6 +392,7 @@ void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
>>>           drm_crtc_commit_put(state->commit);
>>>         drm_property_blob_put(state->fb_damage_clips);
>>> +    drm_property_blob_put(state->solid_fill_blob);
>>>   }
>>>   EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
>>>   diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
>>> index c06d0639d552..8a1d2fb7a757 100644
>>> --- a/drivers/gpu/drm/drm_atomic_uapi.c
>>> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
>>> @@ -316,6 +316,55 @@ drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
>>>   }
>>>   EXPORT_SYMBOL(drm_atomic_set_crtc_for_connector);
>>>   +static void drm_atomic_convert_solid_fill_info(struct drm_solid_fill *out,
>>> +        struct drm_solid_fill_info *in)
>>> +{
>>> +    out->r = in->r;
>>> +    out->g = in->g;
>>> +    out->b = in->b;
>>> +}
>>> +
>>> +static int drm_atomic_set_solid_fill_prop(struct drm_plane_state *state,
>>> +        struct drm_property_blob *blob)
>>> +{
>>> +    int ret = 0;
>>> +    int blob_version;
>>> +
>>> +    if (blob == state->solid_fill_blob)
>>> +        return 0;
>>> +
>>> +    drm_property_blob_put(state->solid_fill_blob);
>>> +    state->solid_fill_blob = NULL;
>>> +
>>> +    memset(&state->solid_fill, 0, sizeof(state->solid_fill));
>>> +
>>> +    if (blob) {
>>> +        if (blob->length != sizeof(struct drm_solid_fill_info)) {
>>> +            drm_dbg_atomic(state->plane->dev,
>>> +                    "[PLANE:%d:%s] bad solid fill blob length: %zu\n",
>>> +                    state->plane->base.id, state->plane->name,
>>> +                    blob->length);
>>> +            return -EINVAL;
>>> +        }
>>> +
>>> +        blob_version = ((struct drm_solid_fill_info *)blob->data)->version;
>>> +
>>> +        /* Append with more versions if necessary */
>>> +        if (blob_version == 1) {
>>> +            drm_atomic_convert_solid_fill_info(&state->solid_fill, blob->data);
>>> +        } else {
>>> +            drm_dbg_atomic(state->plane->dev,
>>> +                    "[PLANE:%d:%s] failed to set solid fill (ret=%d)\n",
>>> +                    state->plane->base.id, state->plane->name,
>>> +                    ret);
>>> +            return -EINVAL;
>>> +        }
>>> +        state->solid_fill_blob = drm_property_blob_get(blob);
>>> +    }
>>> +
>>> +    return ret;
>>> +}
>>> +
>>>   static void set_out_fence_for_crtc(struct drm_atomic_state *state,
>>>                      struct drm_crtc *crtc, s32 __user *fence_ptr)
>>>   {
>>> @@ -544,6 +593,13 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane,
>>>           state->src_w = val;
>>>       } else if (property == config->prop_src_h) {
>>>           state->src_h = val;
>>> +    } else if (property == plane->solid_fill_property) {
>>> +        struct drm_property_blob *solid_fill = drm_property_lookup_blob(dev, val);
>>> +
>>> +        ret = drm_atomic_set_solid_fill_prop(state, solid_fill);
>>> +        drm_property_blob_put(solid_fill);
>>> +
>>> +        return ret;
>>>       } else if (property == plane->alpha_property) {
>>>           state->alpha = val;
>>>       } else if (property == plane->blend_mode_property) {
>>> @@ -616,6 +672,9 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
>>>           *val = state->src_w;
>>>       } else if (property == config->prop_src_h) {
>>>           *val = state->src_h;
>>> +    } else if (property == plane->solid_fill_property) {
>>> +        *val = state->solid_fill_blob ?
>>> +            state->solid_fill_blob->base.id : 0;
>>>       } else if (property == plane->alpha_property) {
>>>           *val = state->alpha;
>>>       } else if (property == plane->blend_mode_property) {
>>> diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
>>> index b4c8cab7158c..17ab645c8309 100644
>>> --- a/drivers/gpu/drm/drm_blend.c
>>> +++ b/drivers/gpu/drm/drm_blend.c
>>> @@ -616,3 +616,20 @@ int drm_plane_create_blend_mode_property(struct drm_plane *plane,
>>>       return 0;
>>>   }
>>>   EXPORT_SYMBOL(drm_plane_create_blend_mode_property);
>>> +
>>> +int drm_plane_create_solid_fill_property(struct drm_plane *plane)
>>> +{
>>> +    struct drm_property *prop;
>>> +
>>> +    prop = drm_property_create(plane->dev,
>>> +            DRM_MODE_PROP_ATOMIC | DRM_MODE_PROP_BLOB,
>>> +            "solid_fill", 0);
>>> +    if (!prop)
>>> +        return -ENOMEM;
>>> +
>>> +    drm_object_attach_property(&plane->base, prop, 0);
>>> +    plane->solid_fill_property = prop;
>>> +
>>> +    return 0;
>>> +}
>>> +EXPORT_SYMBOL(drm_plane_create_solid_fill_property);
>>> diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
>>> index 88bdfec3bd88..0338a860b9c8 100644
>>> --- a/include/drm/drm_blend.h
>>> +++ b/include/drm/drm_blend.h
>>> @@ -58,4 +58,5 @@ int drm_atomic_normalize_zpos(struct drm_device *dev,
>>>                     struct drm_atomic_state *state);
>>>   int drm_plane_create_blend_mode_property(struct drm_plane *plane,
>>>                        unsigned int supported_modes);
>>> +int drm_plane_create_solid_fill_property(struct drm_plane *plane);
>>>   #endif
>>> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
>>> index 447e664e49d5..3b9da06f358b 100644
>>> --- a/include/drm/drm_plane.h
>>> +++ b/include/drm/drm_plane.h
>>> @@ -40,6 +40,25 @@ enum drm_scaling_filter {
>>>       DRM_SCALING_FILTER_NEAREST_NEIGHBOR,
>>>   };
>>>   +/**
>>> + * struct drm_solid_fill_info - User info for solid fill planes
>>> + */
>>> +struct drm_solid_fill_info {
>>> +    __u8 version;
>>> +    __u32 r, g, b;
>>> +};
>>> +
>>> +/**
>>> + * struct solid_fill_property - RGB values for solid fill plane
>>> + *
>>> + * Note: This is the V1 for this feature
>>> + */
>>> +struct drm_solid_fill {
>>> +    uint32_t r;
>>> +    uint32_t g;
>>> +    uint32_t b;
>>> +};
>>> +
>>>   /**
>>>    * struct drm_plane_state - mutable plane state
>>>    *
>>> @@ -116,6 +135,23 @@ struct drm_plane_state {
>>>       /** @src_h: height of visible portion of plane (in 16.16) */
>>>       uint32_t src_h, src_w;
>>>   +    /**
>>> +     * @solid_fill_blob:
>>> +     *
>>> +     * Blob containing relevant information for a solid fill plane
>>> +     * including pixel format and data. See
>>> +     * drm_plane_create_solid_fill_property() for more details.
>>> +     */
>>> +    struct drm_property_blob *solid_fill_blob;
>>> +
>>> +    /**
>>> +     * @solid_fill:
>>> +     *
>>> +     * Pixel data for solid fill planes. See
>>> +     * drm_plane_create_solid_fill_property() for more details.
>>> +     */
>>> +    struct drm_solid_fill solid_fill;
>>> +
>>>       /**
>>>        * @alpha:
>>>        * Opacity of the plane with 0 as completely transparent and 0xffff as
>>> @@ -699,6 +735,13 @@ struct drm_plane {
>>>        */
>>>       struct drm_plane_state *state;
>>>   +    /*
>>> +     * @solid_fill_property:
>>> +     * Optional solid_fill property for this plane. See
>>> +     * drm_plane_create_solid_fill_property().
>>> +     */
>>> +    struct drm_property *solid_fill_property;
>>> +
>>>       /**
>>>        * @alpha_property:
>>>        * Optional alpha property for this plane. See
>>