drivers: sn65dsi86: Retry link training up to 10 times
The kernel guys have found that automatic link training from this bridge
can occasionally fail and needs to be retried. They have added up to 10
retries just to be sure, so let's do the same in coreboot.
BUG=b:169535092
Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: I713b6851bd51d3527ed4c6e6407dee6b42d09955
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45882
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c b/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c
index e0058c4..effa841 100644
--- a/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c
+++ b/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c
@@ -415,15 +415,20 @@
sn65dsi86_bridge_dpcd_request(bus, chip,
DP_BRIDGE_CONFIGURATION_SET, 1, DPCD_WRITE, &buf);
- /* semi auto link training mode */
- i2c_writeb(bus, chip, SN_ML_TX_MODE_REG, 0xa);
+ int i; /* Kernel driver suggests to retry this up to 10 times if it fails. */
+ for (i = 0; i < 10; i++) {
+ i2c_writeb(bus, chip, SN_ML_TX_MODE_REG, SEMI_AUTO_LINK_TRAINING);
- if (!wait_ms(500,
- !(i2c_readb(bus, chip, SN_ML_TX_MODE_REG, &buf)) &&
- (buf & NORMAL_MODE))) {
- printk(BIOS_ERR, "ERROR: Link training failed");
+ if (!wait_ms(500, !(i2c_readb(bus, chip, SN_ML_TX_MODE_REG, &buf)) &&
+ (buf == NORMAL_MODE || buf == MAIN_LINK_OFF))) {
+ printk(BIOS_ERR, "ERROR: unexpected link training state: %#x\n", buf);
+ return;
+ }
+ if (buf == NORMAL_MODE)
+ return;
}
+ printk(BIOS_ERR, "ERROR: Link training failed 10 times\n");
}
static enum cb_err sn65dsi86_bridge_get_plug_in_status(uint8_t bus, uint8_t chip)