[PATCH 10/10] drm/imx: ipuv3-plane: use drm_plane_helper_check_state, clipped coordinates

[Philipp Zabel]

Am Donnerstag, den 20.10.2016, 16:51 +0800 schrieb Ying Liu:
> >> Does the clip thing potentially change the user's request by force?
> >> For example, the user request an unreasonable big resolution.
> >
> > The user is allowed to ask for destination coordinates extending outside
> > the crtc dimensions. This will chop off the parts that aren't visible,
> > and it will chop off the corresponding areas of the source as well.
> 
> How about returning -EINVAL in this case which stands for
> an atomic check failure?

Say the user requests to display a 640x480+0,0 source framebuffer at
destination offset -320,0 on a 320x240 screen, unscaled. The expectation
would be to see the upper right quarter of the framebuffer on the
screen, at least if the hardware was actually able to position overlays
partially offscreen.
If we can also fulfill that expectation by clipping the source rectangle
to 320,240+320,0 and changing the destination rectangle to 320x240+0,0,
why should -EINVAL be returned?

regards
Philipp