From 7618138d8b40adfea7660ccabbb6b131d72e444b Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Wed, 31 May 2017 20:05:35 +0300
Subject: [PATCH] drm/i915/ddi: Avoid long delays during system suspend / eDP disabling
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Git-commit: 7618138d8b40adfea7660ccabbb6b131d72e444b
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900
Atm disabling either DP or eDP outputs can generate a spurious short
pulse interrupt. The reason is that after disabling the port the source
will stop sending a valid stream data, while the sink expects either a
valid stream or the idle pattern. Since neither of this is sent the sink
assumes (after an arbitrary delay) that the link is lost and requests
for link retraining with a short pulse.
The spurious pulse is a real problem at least for eDP panels with long
power-off / power-cycle delays: as part of disabling the output we
disable the panel power. The subsequent spurious short pulse handling
will have to turn the power back on, which means the driver has to do a
redundant wait for the power-off and power-cycle delays. During system
suspend this leads to an unnecessary delay up to ~1s on systems with
such panels as reported by Rui.
To fix this put the sink to DPMS D3 state before turning off the port.
According to the DP spec in this state the sink should not request
retraining. This is also what we do already on pre-ddi platforms.
As an alternative I also tried configuring the port to send idle pattern
- which is against BSPec - and leave the port in normal mode before
turning off the port. Neither of these resolved the problem.
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: David Weinehall <david.weinehall@linux.intel.com>
Cc: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Reported-and-tested-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1496250335-7627-1-git-send-email-imre.deak@intel.com
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/i915/intel_ddi.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1732,12 +1732,18 @@ static void intel_ddi_post_disable(struc
struct drm_i915_private *dev_priv = to_i915(encoder->dev);
enum port port = intel_ddi_get_encoder_port(intel_encoder);
struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
+ struct intel_dp *intel_dp = NULL;
int type = intel_encoder->type;
uint32_t val;
bool wait = false;
/* old_crtc_state and old_conn_state are NULL when called from DP_MST */
+ if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
+ intel_dp = enc_to_intel_dp(encoder);
+ intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+ }
+
val = I915_READ(DDI_BUF_CTL(port));
if (val & DDI_BUF_CTL_ENABLE) {
val &= ~DDI_BUF_CTL_ENABLE;
@@ -1753,9 +1759,7 @@ static void intel_ddi_post_disable(struc
if (wait)
intel_wait_ddi_buf_idle(dev_priv, port);
- if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
- struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
- intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
+ if (intel_dp) {
intel_edp_panel_vdd_on(intel_dp);
intel_edp_panel_off(intel_dp);
}