[RFCv3 03/14] drm: Add primary plane helpers

[Rob Clark]

On Wed, Mar 19, 2014 at 7:28 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
>> +     /*
>> +      * set_config() adjusts crtc->primary->fb; however the DRM setplane
>> +      * code that called us expects to handle the framebuffer update and
>> +      * reference counting; save and restore the current fb before
>> +      * calling it.
>> +      */
>> +     tmpfb = plane->fb;
>> +     ret = crtc->funcs->set_config(&set);
>
> I wonder whether we should have an oppportunistic path using the page_flip
> interface here. Otoh we must have a fallback to ->set_config anyway since
> the drivers currently only allow pageflips on identical buffers. E.g. i915
> rejects tiling changes and stride changes and position changes. So I think
> having a pageflip fastpath isn't worth the trouble.


note that you'd get that opportunistic page_flip() path w/ the
addition of atomic series.  Although depending on when the two
different series are merged, the .page_flip() fast path might be a
good idea