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From:   Mario Limonciello <mario.limonciello@amd.com>
To:     Mika Westerberg <mika.westerberg@linux.intel.com>
CC:     "open list:THUNDERBOLT DRIVER" <linux-usb@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <Sanju.Mehta@amd.com>,
        Mario Limonciello <mario.limonciello@amd.com>
Subject: [PATCH v2 1/5] thunderbolt: Retry DROM reads for more failure scenarios
Date:   Thu, 3 Mar 2022 07:13:24 -0600
Message-ID: <20220303131328.4150454-1-mario.limonciello@amd.com>
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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@amd.com>
---
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