[RFC PATCH xserver] modesetting: re-set the crtc's mode when link-status goes BAD
eric at anholt.net
Fri Mar 31 20:08:41 UTC 2017
Manasi Navare <manasi.d.navare at intel.com> writes:
> 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.
So the kernel will sometimes allow the same mode to be re-set with the
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