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path: root/drivers/gpu/drm/i915/intel_dp.c
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Diffstat (limited to 'drivers/gpu/drm/i915/intel_dp.c')
-rw-r--r--drivers/gpu/drm/i915/intel_dp.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 2151d13772b8..79c14e298ba6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -588,7 +588,18 @@ 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",