Re: [PATCH 1/2] drm/i915: add sanity checks for hsync and htotal

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 21 Jun 2012, Adam Jackson <ajax@redhat.com> wrote:
> On Wed, 2012-06-20 at 23:15 +0300, Jani Nikula wrote:
>> Restrict hsync start, end, hdisplay and htotal to be according to hw
>> spec. Through drm_mode_set_crtcinfo(), these will also limit hblank start,
>> end.
>
> I'm pretty sure any physical hardware would balk at modes like this.
> Virtual framebuffers probably wouldn't care, I guess.  Still, seems
> wrong to have this in i915 when it should be common.
>
> Is this a problem we've seen in the wild, or is this just paranoia?

Looking at patch 2/2 I thought this would be a sensible thing to
do. That patch adds a check for a condition people might expect to work,
but doesn't, on Cantiga and later. It seemed a bit odd to merely add a
check for hsync_start == hdisplay while hsync_start < hdisplay (and the
other related conditions) would fail too.

BR,
Jani.