[Intel-gfx] [PATCH] drm/i915: Allow user modes to exceed DVI 165MHz limit

[Chris Wilson]

On Thu, Mar 27, 2014 at 11:08:45AM +0200, ville.syrjala at linux.intel.com wrote:
> So relax the checks a bit, and apply the single-link DVI dotclock limit
> only when filtering the mode list, and ignore the limit when setting
> a user specified mode.

Mind enlightening me as to how this actually works? I thought all
display modes were validated before we used them, so how come this
sneaks through?

So it goes like this:

userspace calls GETCONNECTOR
kernel: fill_modes -> drm_helper_probe_single_connector_modes -> mode_valid?

but

userspace calls SETCRTC with a random mode
kernel: applies random mode without validation

Seriously we don't do any checking that the mode given to SETCRTC is
applicable and not in any way harmful before setting registers?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre