On Thu, May 14, 2015 at 09:49:52AM -0400, Alex Deucher wrote:
> On Tue, May 12, 2015 at 8:04 PM, Dave Jones <davej at codemonkey.org.uk>
> wrote:
> > On Mon, May 11, 2015 at 03:59:55PM -0400, Alex Deucher wrote:
> >
> > > > I tried tweaking the delays in
> > drm_dp_link_train_clock_recovery_delay, without any noticable
> > > > difference. Is there something else I can try to make it try harder
> > before giving up?
> > > >
> > >
> > > Can you attach your boot dmesg output with drm.debug=0xf set?
> > >
> > > You might also check the dpcd values in the driver during boot up and
> > > link training. There appears to be an issue where that data gets
> > > corrupted in some cases:
> > > https://bugs.freedesktop.org/show_bug.cgi?id=73530
> >
> > I tried both the 'disable spread spectrum' and 'grab dpcd info from vbios
> > for eDP'
> > patches from that bug. Again, no obvious difference.
> >
> > Log from kernel with both applied attached.
> >
> > Also a log file from after I woke up the LCD when it was in sleep mode.
> >
> > Something else curious is how it only discovers a maximum mode from the LCD
> > of 1024x768.
>
> I looks like the monitor is not responding. I'm not entirely sure
> what's going on. I posted a new debugging patch on the bug report
> that will dump the dpcd at various times to see if and when it's
> getting corrupt. Fixing that should at least get the monitor to come
> up reliably (assuming you are experiencing the same issue).
Thanks to some back-and-forth on irc, airlied got this mostly working.
The working combo seems to be..
- Switch monitor to DP 1.2
- boot with radeon.mst=1
- apply the patch below
With all that, it boots up, and X starts up in 2560x1440 like it should.
The only remaining problem is there are some visible glitches, mostly noticable
while scrolling a terminal.
Happy to continue applying further debug patches if you have any more ideas.
thanks,
Dave
diff --git a/drivers/gpu/drm/radeon/radeon_dp_auxch.c
b/drivers/gpu/drm/radeon/radeon_dp_auxch.c
index bf1fecc6cceb..3b401cc8d209 100644
--- a/drivers/gpu/drm/radeon/radeon_dp_auxch.c
+++ b/drivers/gpu/drm/radeon/radeon_dp_auxch.c
@@ -30,7 +30,6 @@
AUX_SW_RX_HPD_DISCON | \
AUX_SW_RX_PARTIAL_BYTE | \
AUX_SW_NON_AUX_MODE | \
- AUX_SW_RX_MIN_COUNT_VIOL | \
AUX_SW_RX_INVALID_STOP | \
AUX_SW_RX_SYNC_INVALID_L | \
AUX_SW_RX_SYNC_INVALID_H | \
