[PATCH 2/2] drm/i915/dp: update training set in a burst write with training pattern set

Jani Nikula
2013-10-04T12:06:25Z

The DP spec allows this, and requires it when full link training is
started with non-minimum voltage swing and/or non-zero pre-emphasis.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
drivers/gpu/drm/i915/intel_dp.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 0ed7717..bfd0e76 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2314,7 +2314,8 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
struct drm_device *dev = intel_dig_port->base.base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
enum port port = intel_dig_port->port;
- int ret;
+ uint8_t buf[sizeof(intel_dp->train_set) + 1];
+ int ret, len;

if (HAS_DDI(dev)) {
uint32_t temp = I915_READ(DP_TP_CTL(port));
@@ -2384,22 +2385,21 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
I915_WRITE(intel_dp->output_reg, *DP);
POSTING_READ(intel_dp->output_reg);

- ret = intel_dp_aux_native_write_1(intel_dp, DP_TRAINING_PATTERN_SET,
- dp_train_pat);
- if (ret != 1)
- return false;
-
- if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) !=
+ buf[0] = dp_train_pat;
+ if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
DP_TRAINING_PATTERN_DISABLE) {
- ret = intel_dp_aux_native_write(intel_dp,
- DP_TRAINING_LANE0_SET,
- intel_dp->train_set,
- intel_dp->lane_count);
- if (ret != intel_dp->lane_count)
- return false;
+ /* don't write DP_TRAINING_LANEx_SET on disable */
+ len = 1;
+ } else {
+ /* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
+ memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
+ len = intel_dp->lane_count + 1;
}

- return true;
+ ret = intel_dp_aux_native_write(intel_dp, DP_TRAINING_PATTERN_SET,
+ buf, len);
+
+ return ret == len;
}

static bool
--
1.7.9.5