@@ -631,7 +631,18 @@ intel_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
DRM_DEBUG_KMS("aux_ch native nack\n");
return -EREMOTEIO;
case AUX_NATIVE_REPLY_DEFER:
- udelay(100);
+ /*
+ * For now, just give more slack to branch devices. We
+ * could check the DPCD for I2C bit rate capabilities,
+ * and if available, adjust the interval. We could also
+ * be more careful with DP-to-Legacy adapters where a
+ * long legacy cable may force very low I2C bit rates.
+ */
+ if (intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+ DP_DWN_STRM_PORT_PRESENT)
+ usleep_range(500, 600);
+ else
+ usleep_range(300, 400);
continue;
default:
DRM_ERROR("aux_ch invalid native reply 0x%02x\n",
This is a note to let you know that I have just added a patch titled drm/i915/dp: increase i2c-over-aux retry interval on AUX to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 29b9bc7b7717593e5027eb33ef4643466452da6e Mon Sep 17 00:00:00 2001 From: Jani Nikula <jani.nikula@intel.com> Date: Fri, 20 Sep 2013 16:42:15 +0300 Subject: [PATCH] drm/i915/dp: increase i2c-over-aux retry interval on AUX DEFER commit 8d16f258217f2f583af1fd57c5144aa4bbe73e48 upstream. There is no clear cut rules or specs for the retry interval, as there are many factors that affect overall response time. Increase the interval, and even more so on branch devices which may have limited i2c bit rates. Signed-off-by: Jani Nikula <jani.nikula@intel.com> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=60263 Tested-by: Nicolas Suzor <nic@suzor.com> Reviewed-by: Todd Previte <tprevite@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/gpu/drm/i915/intel_dp.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) -- 1.8.3.2