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

[Matt Roper <matthew.d.roper@intel.com>]

On Wed, Mar 19, 2014 at 12:28:43PM +0100, Daniel Vetter wrote:
> On Tue, Mar 18, 2014 at 05:22:48PM -0700, Matt Roper 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.
> 
> Also I think you need to use set_config_internal here to get the
> refcounting right.

Hmm.  I specifically didn't use set_config_internal here because I
thought drm_mode_setplane() (and presumably the future atomic ioctl
which may also call into this) will already handle the refcounting for
us.  Am I overlooking something?


Matt

-- 
Matt Roper
Graphics Software Engineer
ISG Platform Enabling & Development
Intel Corporation
(916) 356-2795