Re: Radeon Verde displayport failure.

From: Dave Jones <davej@codemonkey.org.uk>
To: Alex Deucher <alexdeucher@gmail.com>
Cc: "Deucher, Alexander" <Alexander.Deucher@amd.com>,
	"Koenig, Christian" <Christian.Koenig@amd.com>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>
Subject: Re: Radeon Verde displayport failure.
Date: Thu, 14 May 2015 23:52:26 -0400	[thread overview]
Message-ID: <20150515035226.GA9432@codemonkey.org.uk> (raw)
In-Reply-To: <CADnq5_O+jozqExZWjN3C2HZ7=T+KkNy9BUeeqBZbykfRzyXa9A@mail.gmail.com>

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@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 |	     \
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