Comment claims link needs to be retrained because the connected sink raised
a long pulse to indicate link loss. If the sink did so,
intel_dp_hotplug() would have handled link retraining. Looking at the
logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re-apply
Perform link quality check, unconditionally during long pulse"")', the
issue is that the sink does not trigger an interrupt. We want the
->detect() from user space to check link status and retrain. Ville's
review for the original patch also indicates the same root cause.I have also renamed long_pulse() to full_detect(). v2: Patch split and rewrote comment.. Cc: Lyude Paul <[email protected]> Cc: Ville Syrjälä <[email protected]> Cc: Jani Nikula <[email protected]> Cc: Rodrigo Vivi <[email protected]> Cc: Jan-Marek Glogowski <[email protected]> References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"") Signed-off-by: Dhinakaran Pandiyan <[email protected]> --- drivers/gpu/drm/i915/intel_dp.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 436c22de33b6..cac1c7c6cbfd 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -5074,16 +5074,8 @@ intel_dp_long_pulse(struct intel_connector *connector, goto out; } else { /* - * If display is now connected check links status, - * there has been known issues of link loss triggering - * long pulse. - * - * Some sinks (eg. ASUS PB287Q) seem to perform some - * weird HPD ping pong during modesets. So we can apparently - * end up with HPD going low during a modeset, and then - * going back up soon after. And once that happens we must - * retrain the link to get a picture. That's in case no - * userspace component reacted to intermittent HPD dip. + * Some monitors do not signal loss of link synchronization + * with an IRQ_HPD, so force a link status check. */ struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base; -- 2.14.1 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
