[PATCH v2 1/5] thunderbolt: Retry DROM reads for more failure scenarios

From: Mario Limonciello
Date: Thu Mar 03 2022 - 08:15:48 EST


Currently DROM reads are only retried in the case that parsing failed.
However if the size or CRC fails, then there should also be a retry.

This helps with reading the DROM on TBT3 devices connected to AMD
Yellow Carp which will sometimes fail on the first attempt.

Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
v1->v2:
* Update commit message
drivers/thunderbolt/eeprom.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
index 470885e6f1c8..10cdbcb55df9 100644
--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -553,9 +553,9 @@ static int tb_drom_parse(struct tb_switch *sw)
crc = tb_crc8((u8 *) &header->uid, 8);
if (crc != header->uid_crc8) {
tb_sw_warn(sw,
- "DROM UID CRC8 mismatch (expected: %#x, got: %#x), aborting\n",
+ "DROM UID CRC8 mismatch (expected: %#x, got: %#x)\n",
header->uid_crc8, crc);
- return -EINVAL;
+ return -EILSEQ;
}
if (!sw->uid)
sw->uid = header->uid;
@@ -654,6 +654,7 @@ int tb_drom_read(struct tb_switch *sw)
sw->drom = kzalloc(size, GFP_KERNEL);
if (!sw->drom)
return -ENOMEM;
+read:
res = tb_drom_read_n(sw, 0, sw->drom, size);
if (res)
goto err;
@@ -662,7 +663,11 @@ int tb_drom_read(struct tb_switch *sw)
header = (void *) sw->drom;

if (header->data_len + TB_DROM_DATA_START != size) {
- tb_sw_warn(sw, "drom size mismatch, aborting\n");
+ tb_sw_warn(sw, "drom size mismatch\n");
+ if (retries--) {
+ msleep(100);
+ goto read;
+ }
goto err;
}

@@ -683,11 +688,9 @@ int tb_drom_read(struct tb_switch *sw)

/* If the DROM parsing fails, wait a moment and retry once */
if (res == -EILSEQ && retries--) {
- tb_sw_warn(sw, "parsing DROM failed, retrying\n");
+ tb_sw_warn(sw, "parsing DROM failed\n");
msleep(100);
- res = tb_drom_read_n(sw, 0, sw->drom, size);
- if (!res)
- goto parse;
+ goto read;
}

if (!res)
--
2.34.1