On Sun, 2016-07-24 at 16:41 -0700, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> On Wed, Jul 20, 2016 at 08:41:06AM +0000, Joakim Tjernlund wrote:
> >
> > On Tue, 2016-07-19 at 15:06 -0700, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
....
> > > which has a problem with external monitors,
> > > > they go blank/off intermittently. I think/hope this has been fixed upstream by now but I not sure.
> > > > One path caught my eye though was this:
> > > > drm/i915: Revert DisplayPort fast link training feature
> > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/i915?id=34511dc
> > > > e4b3
> > > > 5685d3988d5c8b100d11a068db5bd
> > > >
> > > > Is that one in your queue?
> > >
> > > Yes it is, I have not gotten to that one yet.
> > >
> >
> > I did a quick backport of above patch for 4.4 and had a guy test it his laptop and it did
> > fix the problem :)
>
> Can you provide the backport for 4.4 and 4.6-stable trees, as it
> currently does not apply for me at all :(
>
Just did a backport to 4.4( I hope it applies to 4.6 as well:) but git send email does not work
ATM because we are moving to a new mail domain and it is not finished yet. Attaching the patch instead.
From c403c1a872705d440a4c03b14618adfb36c93568 Mon Sep 17 00:00:00 2001
From: Mika Kahola <mika.kahola@xxxxxxxxx>
Date: Mon, 20 Jun 2016 11:10:26 +0300
Subject: [PATCH] drm/i915: Revert DisplayPort fast link training feature
It has been found out that in some HW combination the DisplayPort
fast link training feature caused screen flickering. Let's revert
this feature for now until we can ensure that the feature works for
all platforms.
This is a manual revert of commits 5fa836a9d859 ("drm/i915: DP link
training optimization") and 4e96c97742f4 ("drm/i915: eDP link training
optimization").
Fixes: 5fa836a9d859 ("drm/i915: DP link training optimization")
Fixes: 4e96c97742f4 ("drm/i915: eDP link training optimization")
Cc: <stable@xxxxxxxxxxxxxxx>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91393
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1466410226-19543-1-git-send-email-mika.kahola@xxxxxxxxx
(cherry picked from commit 91df09d92ad82c8778ca218097bf827f154292ca)
Signed-off-by: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx>
---
Backported to 4.4.y branch
drivers/gpu/drm/i915/intel_dp.c | 28 ++--------------------------
drivers/gpu/drm/i915/intel_drv.h | 1 -
2 files changed, 2 insertions(+), 27 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e55a82a..dd5cfd2 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3628,8 +3628,7 @@ static bool
intel_dp_reset_link_train(struct intel_dp *intel_dp, uint32_t *DP,
uint8_t dp_train_pat)
{
- if (!intel_dp->train_set_valid)
- memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
+ memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
intel_dp_set_signal_levels(intel_dp, DP);
return intel_dp_set_link_train(intel_dp, DP, dp_train_pat);
}
@@ -3746,22 +3745,6 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
break;
}
- /*
- * if we used previously trained voltage and pre-emphasis values
- * and we don't get clock recovery, reset link training values
- */
- if (intel_dp->train_set_valid) {
- DRM_DEBUG_KMS("clock recovery not ok, reset");
- /* clear the flag as we are not reusing train set */
- intel_dp->train_set_valid = false;
- if (!intel_dp_reset_link_train(intel_dp, &DP,
- DP_TRAINING_PATTERN_1 |
- DP_LINK_SCRAMBLING_DISABLE)) {
- DRM_ERROR("failed to enable link training\n");
- return;
- }
- continue;
- }
/* Check to see if we've tried the max voltage */
for (i = 0; i < intel_dp->lane_count; i++)
@@ -3854,7 +3837,6 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
/* Make sure clock is still ok */
if (!drm_dp_clock_recovery_ok(link_status,
intel_dp->lane_count)) {
- intel_dp->train_set_valid = false;
intel_dp_link_training_clock_recovery(intel_dp);
intel_dp_set_link_train(intel_dp, &DP,
training_pattern |
@@ -3871,7 +3853,6 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
/* Try 5 times, then try clock recovery if that fails */
if (tries > 5) {
- intel_dp->train_set_valid = false;
intel_dp_link_training_clock_recovery(intel_dp);
intel_dp_set_link_train(intel_dp, &DP,
training_pattern |
@@ -3893,10 +3874,8 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
intel_dp->DP = DP;
- if (channel_eq) {
- intel_dp->train_set_valid = true;
+ if (channel_eq)
DRM_DEBUG_KMS("Channel EQ done. DP Training successful\n");
- }
}
void intel_dp_stop_link_train(struct intel_dp *intel_dp)
@@ -5157,9 +5136,6 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
intel_display_power_get(dev_priv, power_domain);
if (long_hpd) {
- /* indicate that we need to restart link training */
- intel_dp->train_set_valid = false;
-
if (!intel_digital_port_connected(dev_priv, intel_dig_port))
goto mst_fail;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index f34a219..c5f11e0 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -783,7 +783,6 @@ struct intel_dp {
bool has_aux_irq,
int send_bytes,
uint32_t aux_clock_divider);
- bool train_set_valid;
/* Displayport compliance testing */
unsigned long compliance_test_type;
--
2.7.3