diff options
Diffstat (limited to '0003-drm-i915-dp-Prevent-setting-the-LTTPR-LT-mode-if-no-LTTPRs-are-detected.patch')
| -rw-r--r-- | 0003-drm-i915-dp-Prevent-setting-the-LTTPR-LT-mode-if-no-LTTPRs-are-detected.patch | 115 |
1 files changed, 0 insertions, 115 deletions
diff --git a/0003-drm-i915-dp-Prevent-setting-the-LTTPR-LT-mode-if-no-LTTPRs-are-detected.patch b/0003-drm-i915-dp-Prevent-setting-the-LTTPR-LT-mode-if-no-LTTPRs-are-detected.patch deleted file mode 100644 index 545767e..0000000 --- a/0003-drm-i915-dp-Prevent-setting-the-LTTPR-LT-mode-if-no-LTTPRs-are-detected.patch +++ /dev/null @@ -1,115 +0,0 @@ -From 20a122b58cc3df0134c81396a7591397b8f361f2 Mon Sep 17 00:00:00 2001 -From: Imre Deak <imre.deak@intel.com> -Date: Mon, 18 Jan 2021 20:31:43 +0200 -Subject: drm/i915/dp: Prevent setting the LTTPR LT mode if no LTTPRs are - detected - -Cherry-picked from 3b7bbb3619d2cc92f04ba10ad27d3b616aabf175 - -Atm, the driver programs explicitly the default transparent link -training mode (0x55) to DP_PHY_REPEATER_MODE even if no LTTPRs are -detected. - -This conforms to the spec (3.6.6.1): -"DP upstream devices that do not enable the Non-transparent mode of - LTTPRs shall program the PHY_REPEATER_MODE register (DPCD Address - F0003h) to 55h (default) prior to link training" - -however writing the default value to this DPCD register seems to cause -occasional link training errors at least for a DELL WD19TB TBT dock, when -no LTTPRs are detected. - -Writing to DP_PHY_REPEATER_MODE will also cause an unnecessary timeout -on systems without any LTTPR. - -To fix the above two issues let's assume that setting the default mode -is redundant when no LTTPRs are detected. Keep the existing behavior and -program the default mode if more than 8 LTTPRs are detected or in case -the read from DP_PHY_REPEATER_CNT returns an invalid value. - -References: https://gitlab.freedesktop.org/drm/intel/-/issues/2801 -Signed-off-by: Imre Deak <imre.deak@intel.com> -Reviewed-by: Khaled Almahallawy <khaled.almahallawy@intel.com> -Link: https://patchwork.freedesktop.org/patch/msgid/20210118183143.1145707-1-imre.deak@intel.com ---- - .../gpu/drm/i915/display/intel_dp_link_training.c | 36 +++++++++------------- - 1 file changed, 15 insertions(+), 21 deletions(-) - -diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c -index f916b9f04b6b..0359d5936901 100644 ---- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c -+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c -@@ -34,18 +34,6 @@ intel_dp_dump_link_status(const u8 link_status[DP_LINK_STATUS_SIZE]) - link_status[3], link_status[4], link_status[5]); - } - --static int intel_dp_lttpr_count(struct intel_dp *intel_dp) --{ -- int count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps); -- -- /* -- * Pretend no LTTPRs in case of LTTPR detection error, or -- * if too many (>8) LTTPRs are detected. This translates to link -- * training in transparent mode. -- */ -- return count <= 0 ? 0 : count; --} -- - static void intel_dp_reset_lttpr_count(struct intel_dp *intel_dp) - { - intel_dp->lttpr_common_caps[DP_PHY_REPEATER_CNT - -@@ -151,6 +139,17 @@ int intel_dp_lttpr_init(struct intel_dp *intel_dp) - int i; - - ret = intel_dp_read_lttpr_common_caps(intel_dp); -+ if (!ret) -+ return 0; -+ -+ lttpr_count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps); -+ /* -+ * Prevent setting LTTPR transparent mode explicitly if no LTTPRs are -+ * detected as this breaks link training at least on the Dell WD19TB -+ * dock. -+ */ -+ if (lttpr_count == 0) -+ return 0; - - /* - * See DP Standard v2.0 3.6.6.1. about the explicit disabling of -@@ -159,17 +158,12 @@ int intel_dp_lttpr_init(struct intel_dp *intel_dp) - */ - intel_dp_set_lttpr_transparent_mode(intel_dp, true); - -- if (!ret) -- return 0; -- -- lttpr_count = intel_dp_lttpr_count(intel_dp); -- - /* - * In case of unsupported number of LTTPRs or failing to switch to - * non-transparent mode fall-back to transparent link training mode, - * still taking into account any LTTPR common lane- rate/count limits. - */ -- if (lttpr_count == 0) -+ if (lttpr_count < 0) - return 0; - - if (!intel_dp_set_lttpr_transparent_mode(intel_dp, false)) { -@@ -231,11 +225,11 @@ intel_dp_phy_is_downstream_of_source(struct intel_dp *intel_dp, - enum drm_dp_phy dp_phy) - { - struct drm_i915_private *i915 = dp_to_i915(intel_dp); -- int lttpr_count = intel_dp_lttpr_count(intel_dp); -+ int lttpr_count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps); - -- drm_WARN_ON_ONCE(&i915->drm, lttpr_count == 0 && dp_phy != DP_PHY_DPRX); -+ drm_WARN_ON_ONCE(&i915->drm, lttpr_count <= 0 && dp_phy != DP_PHY_DPRX); - -- return lttpr_count == 0 || dp_phy == DP_PHY_LTTPR(lttpr_count - 1); -+ return lttpr_count <= 0 || dp_phy == DP_PHY_LTTPR(lttpr_count - 1); - } - - static u8 intel_dp_phy_voltage_max(struct intel_dp *intel_dp, --- -cgit v1.2.3-1-gf6bb5 - |