The current link training code does unnecessary retry-loops, and does
extra writes to the registers. It is easier to follow the flow and
ensure it's similar to Toshiba's documentation if we deal with LT inside
tc_main_link_enable() function.
This patch adds tc_wait_link_training() which handles waiting for the LT
phase to finish, and does the necessary LT register setups in
tc_main_link_enable, without extra loops.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
---
drivers/gpu/drm/bridge/tc358767.c | 136 +++++++++++++-----------------
1 file changed, 60 insertions(+), 76 deletions(-)
diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index d79b1d0ca0db..10a9b46de5f1 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -740,84 +740,24 @@ static int tc_set_video_mode(struct tc_data *tc,
return ret;
}
-static int tc_link_training(struct tc_data *tc, int pattern)
+static int tc_wait_link_training(struct tc_data *tc)
{
- const char * const *errors;
- u32 srcctrl = tc_srcctrl(tc) | DP0_SRCCTRL_SCRMBLDIS |
- DP0_SRCCTRL_AUTOCORRECT;
- int timeout;
- int retry;
+ u32 timeout = 1000;
u32 value;
int ret;
- if (pattern == DP_TRAINING_PATTERN_1) {
- srcctrl |= DP0_SRCCTRL_TP1;
- errors = training_pattern1_errors;
- } else {
- srcctrl |= DP0_SRCCTRL_TP2;
- errors = training_pattern2_errors;
- }
-
- /* Set DPCD 0x102 for Training Part 1 or 2 */
- tc_write(DP0_SNKLTCTRL, DP_LINK_SCRAMBLING_DISABLE | pattern);
-
- tc_write(DP0_LTLOOPCTRL,
- (0x0f << 28) | /* Defer Iteration Count */
- (0x0f << 24) | /* Loop Iteration Count */
- (0x0d << 0)); /* Loop Timer Delay */
-
- retry = 5;
do {
- /* Set DP0 Training Pattern */
- tc_write(DP0_SRCCTRL, srcctrl);
-
- /* Enable DP0 to start Link Training */
- tc_write(DP0CTL, DP_EN);
-
- /* wait */
- timeout = 1000;
- do {
- tc_read(DP0_LTSTAT, &value);
- udelay(1);
- } while ((!(value & LT_LOOPDONE)) && (--timeout));
- if (timeout == 0) {
- dev_err(tc->dev, "Link training timeout!\n");
- } else {
- int pattern = (value >> 11) & 0x3;
- int error = (value >> 8) & 0x7;
-
- dev_dbg(tc->dev,
- "Link training phase %d done after %d uS: %s\n",
- pattern, 1000 - timeout, errors[error]);
- if (pattern == DP_TRAINING_PATTERN_1 && error == 0)
- break;
- if (pattern == DP_TRAINING_PATTERN_2) {
- value &= LT_CHANNEL1_EQ_BITS |
- LT_INTERLANE_ALIGN_DONE |
- LT_CHANNEL0_EQ_BITS;
- /* in case of two lanes */
- if ((tc->link.base.num_lanes == 2) &&
- (value == (LT_CHANNEL1_EQ_BITS |
- LT_INTERLANE_ALIGN_DONE |
- LT_CHANNEL0_EQ_BITS)))
- break;
- /* in case of one line */
- if ((tc->link.base.num_lanes == 1) &&
- (value == (LT_INTERLANE_ALIGN_DONE |
- LT_CHANNEL0_EQ_BITS)))
- break;
- }
- }
- /* restart */
- tc_write(DP0CTL, 0);
- usleep_range(10, 20);
- } while (--retry);
- if (retry == 0) {
- dev_err(tc->dev, "Failed to finish training phase %d\n",
- pattern);
+ udelay(1);
+ tc_read(DP0_LTSTAT, &value);
+ } while ((!(value & LT_LOOPDONE)) && (--timeout));
+
+ if (timeout == 0) {
+ dev_err(tc->dev, "Link training timeout waiting for LT_LOOPDONE!\n");
+ return -ETIMEDOUT;
}
- return 0;
+ return (value >> 8) & 0x7;
+
err:
return ret;
}
@@ -927,7 +867,7 @@ static int tc_main_link_enable(struct tc_data *tc)
if (tmp[0] != tc->assr) {
dev_dbg(dev, "Failed to switch display ASSR to %d, falling back to unscrambled mode\n",
- tc->assr);
+ tc->assr);
/* trying with disabled scrambler */
tc->link.scrambler_dis = true;
}
@@ -953,13 +893,57 @@ static int tc_main_link_enable(struct tc_data *tc)
if (ret < 0)
goto err_dpcd_write;
- ret = tc_link_training(tc, DP_TRAINING_PATTERN_1);
- if (ret)
+ /* Clock-Recovery */
+
+ /* Set DPCD 0x102 for Training Pattern 1 */
+ tc_write(DP0_SNKLTCTRL, DP_LINK_SCRAMBLING_DISABLE |
+ DP_TRAINING_PATTERN_1);
+
+ tc_write(DP0_LTLOOPCTRL,
+ (15 << 28) | /* Defer Iteration Count */
+ (15 << 24) | /* Loop Iteration Count */
+ (0xd << 0)); /* Loop Timer Delay */
+
+ tc_write(DP0_SRCCTRL, tc_srcctrl(tc) | DP0_SRCCTRL_SCRMBLDIS |
+ DP0_SRCCTRL_AUTOCORRECT | DP0_SRCCTRL_TP1);
+
+ /* Enable DP0 to start Link Training */
+ tc_write(DP0CTL,
+ ((tc->link.base.capabilities & DP_LINK_CAP_ENHANCED_FRAMING) ? EF_EN : 0) |
+ DP_EN);
+
+ /* wait */
+ ret = tc_wait_link_training(tc);
+ if (ret < 0)
goto err;
- ret = tc_link_training(tc, DP_TRAINING_PATTERN_2);
- if (ret)
+ if (ret) {
+ dev_err(tc->dev, "Link training phase 1 failed: %s\n",
+ training_pattern1_errors[ret]);
+ ret = -ENODEV;
goto err;
+ }
+
+ /* Channel Equalization */
+
+ /* Set DPCD 0x102 for Training Pattern 2 */
+ tc_write(DP0_SNKLTCTRL, DP_LINK_SCRAMBLING_DISABLE |
+ DP_TRAINING_PATTERN_2);
+
+ tc_write(DP0_SRCCTRL, tc_srcctrl(tc) | DP0_SRCCTRL_SCRMBLDIS |
+ DP0_SRCCTRL_AUTOCORRECT | DP0_SRCCTRL_TP2);
+
+ /* wait */
+ ret = tc_wait_link_training(tc);
+ if (ret < 0)
+ goto err;
+
+ if (ret) {
+ dev_err(tc->dev, "Link training phase 2 failed: %s\n",
+ training_pattern2_errors[ret]);
+ ret = -ENODEV;
+ goto err;
+ }
/*
* Toshiba's documentation suggests to first clear DPCD 0x102, then
--
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