projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| a0cb8bb7 GKH |
1 | From 8d16f258217f2f583af1fd57c5144aa4bbe73e48 Mon Sep 17 00:00:00 2001 |
| 2 | From: Jani Nikula <jani.nikula@intel.com> | |
| 3 | Date: Fri, 20 Sep 2013 16:42:15 +0300 | |
| 4 | Subject: drm/i915/dp: increase i2c-over-aux retry interval on AUX DEFER | |
| 5 | ||
| 6 | From: Jani Nikula <jani.nikula@intel.com> | |
| 7 | ||
| 8 | commit 8d16f258217f2f583af1fd57c5144aa4bbe73e48 upstream. | |
| 9 | ||
| 10 | There is no clear cut rules or specs for the retry interval, as there | |
| 11 | are many factors that affect overall response time. Increase the | |
| 12 | interval, and even more so on branch devices which may have limited i2c | |
| 13 | bit rates. | |
| 14 | ||
| 15 | Signed-off-by: Jani Nikula <jani.nikula@intel.com> | |
| 16 | Reference: https://bugs.freedesktop.org/show_bug.cgi?id=60263 | |
| 17 | Tested-by: Nicolas Suzor <nic@suzor.com> | |
| 18 | Reviewed-by: Todd Previte <tprevite@gmail.com> | |
| 19 | Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> | |
| 20 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 21 | ||
| 22 | --- | |
| 23 | drivers/gpu/drm/i915/intel_dp.c | 13 ++++++++++++- | |
| 24 | 1 file changed, 12 insertions(+), 1 deletion(-) | |
| 25 | ||
| 26 | --- a/drivers/gpu/drm/i915/intel_dp.c | |
| 27 | +++ b/drivers/gpu/drm/i915/intel_dp.c | |
| 28 | @@ -625,7 +625,18 @@ intel_dp_i2c_aux_ch(struct i2c_adapter * | |
| 29 | DRM_DEBUG_KMS("aux_ch native nack\n"); | |
| 30 | return -EREMOTEIO; | |
| 31 | case AUX_NATIVE_REPLY_DEFER: | |
| 32 | - udelay(100); | |
| 33 | + /* | |
| 34 | + * For now, just give more slack to branch devices. We | |
| 35 | + * could check the DPCD for I2C bit rate capabilities, | |
| 36 | + * and if available, adjust the interval. We could also | |
| 37 | + * be more careful with DP-to-Legacy adapters where a | |
| 38 | + * long legacy cable may force very low I2C bit rates. | |
| 39 | + */ | |
| 40 | + if (intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] & | |
| 41 | + DP_DWN_STRM_PORT_PRESENT) | |
| 42 | + usleep_range(500, 600); | |
| 43 | + else | |
| 44 | + usleep_range(300, 400); | |
| 45 | continue; | |
| 46 | default: | |
| 47 | DRM_ERROR("aux_ch invalid native reply 0x%02x\n", |