On Fri, 6 Jan 2023 at 20:41, Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Fri, Jan 06, 2023 at 05:43:23AM +0200, Dmitry Baryshkov wrote: > > On Fri, 6 Jan 2023 at 02:38, Jessica Zhang <quic_jesszhan@xxxxxxxxxxx> wrote: > > > > > > > > > > > > On 1/5/2023 3:33 AM, Daniel Vetter wrote: > > > > On Wed, Jan 04, 2023 at 03:40:33PM -0800, Jessica Zhang wrote: > > > >> Introduce and add support for a solid_fill property. When the solid_fill > > > >> property is set, and the framebuffer is set to NULL, memory fetch will be > > > >> disabled. > > > >> > > > >> In addition, loosen the NULL FB checks within the atomic commit callstack > > > >> to allow a NULL FB when the solid_fill property is set and add FB checks > > > >> in methods where the FB was previously assumed to be non-NULL. > > > >> > > > >> Finally, have the DPU driver use drm_plane_state.solid_fill and instead of > > > >> dpu_plane_state.color_fill, and add extra checks in the DPU atomic commit > > > >> callstack to account for a NULL FB in cases where solid_fill is set. > > > >> > > > >> Some drivers support hardware that have optimizations for solid fill > > > >> planes. This series aims to expose these capabilities to userspace as > > > >> some compositors have a solid fill flag (ex. SOLID_COLOR in the Android > > > >> hardware composer HAL) that can be set by apps like the Android Gears > > > >> app. > > > >> > > > >> Userspace can set the solid_fill property to a blob containing the > > > >> appropriate version number and solid fill color (in RGB323232 format) and > > > >> setting the framebuffer to NULL. > > > >> > > > >> Note: Currently, there's only one version of the solid_fill blob property. > > > >> However if other drivers want to support a similar feature, but require > > > >> more than just the solid fill color, they can extend this feature by > > > >> creating additional versions of the drm_solid_fill struct. > > > >> > > > >> Changes in V2: > > > >> - Dropped SOLID_FILL_FORMAT property (Simon) > > > >> - Switched to implementing solid_fill property as a blob (Simon, Dmitry) > > > >> - Changed to checks for if solid_fill_blob is set (Dmitry) > > > >> - Abstracted (plane_state && !solid_fill_blob) checks to helper method > > > >> (Dmitry) > > > >> - Removed DPU_PLANE_COLOR_FILL_FLAG > > > >> - Fixed whitespace and indentation issues (Dmitry) > > > > > > > > Now that this is a blob, I do wonder again whether it's not cleaner to set > > > > the blob as the FB pointer. Or create some kind other kind of special data > > > > source objects (because solid fill is by far not the only such thing). > > > > > > > > We'd still end up in special cases like when userspace that doesn't > > > > understand solid fill tries to read out such a framebuffer, but these > > > > cases already exist anyway for lack of priviledges. > > > > > > > > So I still think that feels like the more consistent way to integrate this > > > > feature. Which doesn't mean it has to happen like that, but the > > > > patches/cover letter should at least explain why we don't do it like this. > > > > > > Hi Daniel, > > > > > > IIRC we were facing some issues with this check [1] when trying to set > > > FB to a PROP_BLOB instead. Which is why we went with making it a > > > separate property instead. Will mention this in the cover letter. > > > > What kind of issues? Could you please describe them? > > We switched from bitmask to enum style for prop types, which means it's > not possible to express with the current uapi a property which accepts > both an object or a blob. > > Which yeah sucks a bit ... > > But! > > blob properties are kms objects (like framebuffers), so it should be > possible to stuff a blob into an object property as-is. Of course you need > to update the validation code to make sure we accept either an fb or a > blob for the internal representation. But that kind of split internally is > required no matter what I think. I checked your idea and notes from Jessica. So while we can pass blobs to property objects, the prop_fb_id is created as an object property with the type DRM_MODE_OBJECT_FB. Passing DRM_MODE_OBJECT_BLOB would fail a check in drm_property_change_valid_get() -> __drm_mode_object_find(). And I don't think that we should break the existing validation code for this special case. If you insist on using FB_ID for passing solid_fill information, I'd ask you to reconsider using a 1x1 framebuffer. It would be fully compatible with the existing userspace, which can then treat it seamlessly. > -Daniel > > > > > > > > > [1] > > > https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/drm_property.c#L71 -- With best wishes Dmitry
