From 411e7607d677f7679cfe307d4de5de0315f68038 Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Wed, 30 Sep 2020 15:23:46 -0700 Subject: 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 Change-Id: I713b6851bd51d3527ed4c6e6407dee6b42d09955 Reviewed-on: https://review.coreboot.org/c/coreboot/+/45882 Reviewed-by: Douglas Anderson Tested-by: build bot (Jenkins) --- src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c b/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c index e0058c4fe7..effa841690 100644 --- a/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c +++ b/src/drivers/ti/sn65dsi86bridge/sn65dsi86bridge.c @@ -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); - - if (!wait_ms(500, - !(i2c_readb(bus, chip, SN_ML_TX_MODE_REG, &buf)) && - (buf & NORMAL_MODE))) { - printk(BIOS_ERR, "ERROR: Link training failed"); + 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 || 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) -- cgit v1.2.3