Re: [PATCH] video/console: Clip the right margin clear to the visible region

From: Chris Wilson
Date: Fri Mar 30 2012 - 03:56:39 EST

On Fri, 30 Mar 2012 01:16:32 +0000, Florian Tobias Schandinat <FlorianSchandinat@xxxxxx> wrote:
> Hi Chris,
> On 03/26/2012 08:17 PM, Chris Wilson wrote:
> > For some unknown reason, yres_virtual was 2x larger the the size specified
> > by i915 and so when blit_clear_margins() tried to clear the full virtual
> > right-hand margin it tried to write far beyond the end of the buffer.
> >
> > This limits the clear to only the visible portion of the right-hand
> > margin, similar to how the bottom margin is treated.
> >
> > Bugzilla:
> as you also found the root of the problem and posted a patch to fix i915
> (or rather all KMS-based framebuffers) by validating the virtual
> resolution in check var, I don't see any reason to apply this one. I'm
> not sure about it, but changing the behaviour of this function might
> cause some undesired changes in user experience and as there is no
> problem with this code as is, I'd prefer to not change it.

Ok, thanks for the review. Preventing userspace from programming an
unhandled value of yres_virtual is definitely the way forward.

Chris Wilson, Intel Open Source Technology Centre
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