Found this by comparing it to the coreboot driver, a form of this call
was introduced there in their commit b9a7877568cf ("rockchip/*: refactor
edp driver"). This is copy-pasted from U-Boot's link_train_cr() slightly
above it.
Without this on a gru-kevin chromebook, I have:
clock recovery at voltage 0 pre-emphasis 0
requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
using signal parameters: voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
using signal parameters: voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
using signal parameters: voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
using signal parameters: voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
using signal parameters: voltage 0.4V pre_emph 3.5dB
channel eq failed, ret=-5
link train failed!
rk_vop_probe() Device failed: ret=-5
With this, it looks like training succeeds:
clock recovery at voltage 0 pre-emphasis 0
requested signal parameters: lane 0 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 3.5dB
using signal parameters: voltage 0.4V pre_emph 3.5dB
requested signal parameters: lane 0 voltage 0.4V pre_emph 6dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 6dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 6dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 6dB
using signal parameters: voltage 0.4V pre_emph 6dB
requested signal parameters: lane 0 voltage 0.4V pre_emph 0dB
requested signal parameters: lane 1 voltage 0.4V pre_emph 0dB
requested signal parameters: lane 2 voltage 0.4V pre_emph 0dB
requested signal parameters: lane 3 voltage 0.4V pre_emph 0dB
using signal parameters: voltage 0.4V pre_emph 0dB
channel eq at voltage 0 pre-emphasis 0
config video failed
rk_vop_probe() Device failed: ret=-110
The "config video failed" error also goes away when I disable higher
log levels, and it claims to have successfully probed the device.
Signed-off-by: Alper Nebi Yasak <[email protected]>
---
I'm testing this with a lot of other patches to make the board work. The
actual tree I'm using is available here:
https://github.com/alpernebbi/u-boot/commits/rk3399-gru-kevin/wip
(currently at commit c0dc4b42afe770671ce7bb0dd519d894a3acdea0)
drivers/video/rockchip/rk_edp.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/video/rockchip/rk_edp.c b/drivers/video/rockchip/rk_edp.c
index 000bd48140..a032eb6889 100644
--- a/drivers/video/rockchip/rk_edp.c
+++ b/drivers/video/rockchip/rk_edp.c
@@ -559,6 +559,12 @@ static int rk_edp_link_train_ce(struct rk_edp_priv *edp)
channel_eq = 0;
for (tries = 0; tries < 5; tries++) {
rk_edp_set_link_training(edp, edp->train_set);
+ ret = rk_edp_dpcd_write(regs, DPCD_TRAINING_LANE0_SET,
+ edp->train_set,
+ edp->link_train.lane_count);
+ if (ret)
+ return ret;
+
udelay(400);
if (rk_edp_dpcd_read_link_status(edp, status) < 0) {
--
2.28.0
