Julius Werner has submitted this change. ( https://review.coreboot.org/c/coreboot/+/45882 )
Change subject: drivers: sn65dsi86: Retry link training up to 10 times ......................................................................
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 --- M src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c 1 file changed, 11 insertions(+), 6 deletions(-)
Approvals: build bot (Jenkins): Verified Douglas Anderson: Looks good to me, approved
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)