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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>
This commit is contained in:
Julius Werner 2020-09-30 15:23:46 -07:00
parent 768f59a32f
commit 411e7607d6
1 changed files with 11 additions and 6 deletions
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17
src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c
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@ -415,15 +415,20 @@ static void sn65dsi86_bridge_link_training(uint8_t bus, uint8_t chip)
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)