[RFC PATCH xserver] modesetting: re-set the crtc's mode when link-status goes BAD

[Manasi Navare]

On Thu, Mar 30, 2017 at 05:37:55PM -0700, Eric Anholt wrote:
> Martin Peres <martin.peres at linux.intel.com> writes:
> 
> > On 26/01/17 14:37, Martin Peres wrote:
> >> Despite all the careful planing of the kernel, a link may become
> >> insufficient to handle the currently-set mode. At this point, the
> >> kernel should mark this particular configuration as being broken
> >> and potentially prune the mode before setting the offending connector's
> >> link-status to BAD and send the userspace a hotplug event. This may
> >> happen right after a modeset or later on.
> >>
> >> When available, we should use the link-status information to reset
> >> the wanted mode.
> >>
> >> Signed-off-by: Martin Peres <martin.peres at linux.intel.com>
> >
> > The relevant kernel patches have landed in drm-tip about a month ago.
> >
> > Eric, would you mind providing feedback on or merging this patch?
> 
> The later discussion has sounded like the kernel will (always) prune the
> mode when we re-query, meaning that it doesn't make any sense to try to
> re-set to the old mode.  Is this not the case?


No the kernel will simply send a hotplug with link status as bad
and then after that point its userspace driver's responsibility
to check if link status is BAD, retry the same mode and if it fails
then re probe.

Regards
Manasi