From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com ([192.55.52.93]:52101 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753981AbcFTJsJ (ORCPT ); Mon, 20 Jun 2016 05:48:09 -0400 From: Jani Nikula To: Mika Kahola , intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org Subject: Re: [Intel-gfx] [PATCH RESEND] drm/i915: Revert DisplayPort fast link training feature In-Reply-To: <1466410226-19543-1-git-send-email-mika.kahola@intel.com> References: <1466410226-19543-1-git-send-email-mika.kahola@intel.com> Date: Mon, 20 Jun 2016 12:48:06 +0300 Message-ID: <87wplk8a3t.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: stable-owner@vger.kernel.org List-ID: On Mon, 20 Jun 2016, Mika Kahola wrote: > 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: # v4.2+ > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91393 > Reviewed-by: Jani Nikula > Signed-off-by: Mika Kahola Pushed to drm-intel-next-queued, thanks for the patch. BR, Jani. > --- > drivers/gpu/drm/i915/intel_dp.c | 3 --- > drivers/gpu/drm/i915/intel_dp_link_training.c | 26 ++------------------------ > drivers/gpu/drm/i915/intel_drv.h | 2 -- > 3 files changed, 2 insertions(+), 29 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index be08351..3cdea4d7a 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -4621,9 +4621,6 @@ 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; > - > intel_dp_long_pulse(intel_dp->attached_connector); > if (intel_dp->is_mst) > ret = IRQ_HANDLED; > diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c > index 0b8eefc..60fb39c 100644 > --- a/drivers/gpu/drm/i915/intel_dp_link_training.c > +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c > @@ -85,8 +85,7 @@ static bool > intel_dp_reset_link_train(struct intel_dp *intel_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); > return intel_dp_set_link_train(intel_dp, dp_train_pat); > } > @@ -161,23 +160,6 @@ 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_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++) > if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0) > @@ -284,7 +266,6 @@ 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, > training_pattern | > @@ -301,7 +282,6 @@ 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, > training_pattern | > @@ -322,10 +302,8 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp) > > intel_dp_set_idle_link_train(intel_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) > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h > index 0c1dc9b..9257f08 100644 > --- a/drivers/gpu/drm/i915/intel_drv.h > +++ b/drivers/gpu/drm/i915/intel_drv.h > @@ -894,8 +894,6 @@ struct intel_dp { > /* This is called before a link training is starterd */ > void (*prepare_link_retrain)(struct intel_dp *intel_dp); > > - bool train_set_valid; > - > /* Displayport compliance testing */ > unsigned long compliance_test_type; > unsigned long compliance_test_data; -- Jani Nikula, Intel Open Source Technology Center