[Bug 91871] link retraining for DP not possible with current design of Atomic modeset framework

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=91871

--- Comment #4 from Manasi <manasi.d.navare at intel.com> ---
Hi there,

I have been working on a solution for the problem discussed above and how can
we send a notification back to userspace if link training fails during or after
atomic modeset. Like Jani mentioned, in this case we cannot just reduce the
link parameters and retrain the link because the link parameters are already
set to the minimum required for the requested mode. So I have implemented a
solution by adding a link-status property to the connector that will be set to
BAD by the driver as soon as link training fails followed by a uevent sent to
the userspace indicating the HW/connector configuration changed and it needs to
refetch the modes and redo a modeset (effectively at lower mode). This avoids
the problem of black screen on link failure during or after modeset, instead it
retrains the link at lower link parameters and renders the display at lower
resolution/mode resulting in a successful modeset at all times.

Some of the patches related to this are merged, few are still under review
here:
https://patchwork.freedesktop.org/series/16912/

Regards
Manasi

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