2013-03-11 17:40:21

by Takashi Iwai

Subject: [PATCH] Revert "drm/i915: try to train DP even harder"

This reverts commit 0d71068835e2610576d369d6d4cbf90e0f802a71.

Not only that the commit introduces a bogus check (voltage_tries == 5
will never meet at the inserted code path), it brings the i915 driver
into an endless dp-train loop on HP Z1 desktop machine with IVY+eDP.

At least reverting this commit recovers the framebuffer (but X is
still broken by other reasons...)

Cc: <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
---
drivers/gpu/drm/i915/intel_dp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index f61cb79..7d250aa 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1929,7 +1929,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
for (i = 0; i < intel_dp->lane_count; i++)
if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
break;
- if (i == intel_dp->lane_count && voltage_tries == 5) {
+ if (i == intel_dp->lane_count) {
++loop_tries;
if (loop_tries == 5) {
DRM_DEBUG_KMS("too many full retries, give up\n");
--
1.8.1.4

2013-03-17 21:56:39

by Daniel Vetter

Subject: Re: [PATCH] Revert "drm/i915: try to train DP even harder"

On Mon, Mar 11, 2013 at 06:40:16PM +0100, Takashi Iwai wrote:
> This reverts commit 0d71068835e2610576d369d6d4cbf90e0f802a71.
>
> Not only that the commit introduces a bogus check (voltage_tries == 5
> will never meet at the inserted code path), it brings the i915 driver
> into an endless dp-train loop on HP Z1 desktop machine with IVY+eDP.
>
> At least reverting this commit recovers the framebuffer (but X is
> still broken by other reasons...)
>
> Cc: <[email protected]>
> Signed-off-by: Takashi Iwai <[email protected]>
Picked up for -fixes, thanks for the patch. Adding Paulo since it's his
patch. To assign proper blame please cc: relevant people when sending out
reverts.

Thanks, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

2013-03-18 09:10:52

by Takashi Iwai

Subject: Re: [PATCH] Revert "drm/i915: try to train DP even harder"

At Sun, 17 Mar 2013 22:59:22 +0100,
Daniel Vetter wrote:
>
> On Mon, Mar 11, 2013 at 06:40:16PM +0100, Takashi Iwai wrote:
> > This reverts commit 0d71068835e2610576d369d6d4cbf90e0f802a71.
> >
> > Not only that the commit introduces a bogus check (voltage_tries == 5
> > will never meet at the inserted code path), it brings the i915 driver
> > into an endless dp-train loop on HP Z1 desktop machine with IVY+eDP.
> >
> > At least reverting this commit recovers the framebuffer (but X is
> > still broken by other reasons...)
> >
> > Cc: <[email protected]>
> > Signed-off-by: Takashi Iwai <[email protected]>
> Picked up for -fixes, thanks for the patch.

Thanks!

> Adding Paulo since it's his
> patch. To assign proper blame please cc: relevant people when sending out
> reverts.

Well, Paulo was on Cc in the first post, but I dropped in the next
patch series since I've got no reply since then. (And intel-gfx was
on Cc, so he could read it anyway...)


Takashi