From 489375c866c111f16cea93b2467ebe59c9022cc7 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Mon, 24 Oct 2016 19:33:31 +0300 Subject: [PATCH] drm/i915/lspcon: Add workaround for resuming in PCON mode MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On my APL the LSPCON firmware resumes in PCON mode as opposed to the expected LS mode. It also appears to be in a state where AUX DPCD reads will succeed but return garbage recovering only after a few hundreds of milliseconds. After the recovery time DPCD reads will result in the correct values and things will continue to work. If I2C over AUX is attempted during this recovery time (implying an AUX write transaction) the firmware won't recover and will stay in this broken state. As a workaround check if the firmware is in PCON state after resume and if so wait until the correct DPCD values are returned. For this we compare the branch descriptor with the one we cached during init time. If the firmware was in the LS state, we skip the w/a and continue as before. v2: - Use the DP descriptor value cached in intel_dp. (Jani) - Get to intel_dp using container_of(), instead of a cached ptr. (Shashank) - Use usleep_range() instead of msleep(). Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98353 Cc: Shashank Sharma Cc: Ville Syrjälä Cc: Jani Nikula Signed-off-by: Imre Deak Reviewed-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/1477326811-30431-9-git-send-email-imre.deak@intel.com --- drivers/gpu/drm/i915/intel_dp.c | 2 +- drivers/gpu/drm/i915/intel_drv.h | 3 +++ drivers/gpu/drm/i915/intel_lspcon.c | 37 ++++++++++++++++++++++++++++- 3 files changed, 40 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 6eb43647163c..8f313c1d374d 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1451,7 +1451,7 @@ static void intel_dp_print_rates(struct intel_dp *intel_dp) DRM_DEBUG_KMS("common rates: %s\n", str); } -static bool +bool __intel_dp_read_desc(struct intel_dp *intel_dp, struct intel_dp_desc *desc) { u32 base = drm_dp_is_branch(intel_dp->dpcd) ? DP_BRANCH_OUI : diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 5989c48d7964..c2f38634e86e 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -974,6 +974,7 @@ struct intel_dp { struct intel_lspcon { bool active; enum drm_lspcon_mode mode; + bool desc_valid; }; struct intel_digital_port { @@ -1467,6 +1468,8 @@ static inline unsigned int intel_dp_unused_lane_mask(int lane_count) } bool intel_dp_read_dpcd(struct intel_dp *intel_dp); +bool __intel_dp_read_desc(struct intel_dp *intel_dp, + struct intel_dp_desc *desc); bool intel_dp_read_desc(struct intel_dp *intel_dp); /* intel_dp_aux_backlight.c */ diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c index 3dc5a0be7857..daa523410953 100644 --- a/drivers/gpu/drm/i915/intel_lspcon.c +++ b/drivers/gpu/drm/i915/intel_lspcon.c @@ -97,8 +97,43 @@ static bool lspcon_probe(struct intel_lspcon *lspcon) return true; } +static void lspcon_resume_in_pcon_wa(struct intel_lspcon *lspcon) +{ + struct intel_dp *intel_dp = lspcon_to_intel_dp(lspcon); + unsigned long start = jiffies; + + if (!lspcon->desc_valid) + return; + + while (1) { + struct intel_dp_desc desc; + + /* + * The w/a only applies in PCON mode and we don't expect any + * AUX errors. + */ + if (!__intel_dp_read_desc(intel_dp, &desc)) + return; + + if (!memcmp(&intel_dp->desc, &desc, sizeof(desc))) { + DRM_DEBUG_KMS("LSPCON recovering in PCON mode after %u ms\n", + jiffies_to_msecs(jiffies - start)); + return; + } + + if (time_after(jiffies, start + msecs_to_jiffies(1000))) + break; + + usleep_range(10000, 15000); + } + + DRM_DEBUG_KMS("LSPCON DP descriptor mismatch after resume\n"); +} + void lspcon_resume(struct intel_lspcon *lspcon) { + lspcon_resume_in_pcon_wa(lspcon); + if (lspcon_change_mode(lspcon, DRM_LSPCON_MODE_PCON, true)) DRM_ERROR("LSPCON resume failed\n"); else @@ -143,7 +178,7 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port) return false; } - intel_dp_read_desc(dp); + lspcon->desc_valid = intel_dp_read_desc(dp); DRM_DEBUG_KMS("Success: LSPCON init\n"); return true; -- 2.30.2