[PATCH iwl v3] ice: retry reading NVM if admin queue returns EBUSY

[Robert Malz <robert.malz@canonical.com>]

When the admin queue command to read NVM returns EBUSY, the driver
currently treats it as a fatal error and aborts the entire read
operation. This can cause spurious NVM read failures during periods of
high firmware activity.

Add retry logic to ice_read_flat_nvm() that handles EBUSY responses
from the admin queue. When an EBUSY error is encountered, release the
NVM resource lock, wait for ICE_SQ_SEND_DELAY_TIME_MS, re-acquire it,
and retry the failed read. The retry is attempted up to
ICE_SQ_SEND_MAX_EXECUTE times before giving up.

Code was extracted from OOT ice driver 1.15.4 release. Additional
change was made to reset last_cmd in case of retry to make sure that
all commands are retried properly.

Fixes: e94509906d6b ("ice: create function to read a section of the NVM and Shadow RAM")
Signed-off-by: Robert Malz <robert.malz@canonical.com>
---
Changes in v2:
- change ICE_AQ_RC_EBUSY -> LIBIE_AQ_RC_EBUSY
Changes in v3:
- resending to comply with the netdev 24-hour rule. No code changes since v2.

 drivers/net/ethernet/intel/ice/ice_nvm.c | 25 +++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_nvm.c b/drivers/net/ethernet/intel/ice/ice_nvm.c
index 7e187a804dfa..b3120605d66f 100644
--- a/drivers/net/ethernet/intel/ice/ice_nvm.c
+++ b/drivers/net/ethernet/intel/ice/ice_nvm.c
@@ -67,6 +67,7 @@ ice_read_flat_nvm(struct ice_hw *hw, u32 offset, u32 *length, u8 *data,
 {
 	u32 inlen = *length;
 	u32 bytes_read = 0;
+	int retry_cnt = 0;
 	bool last_cmd;
 	int status;
 
@@ -96,11 +97,25 @@ ice_read_flat_nvm(struct ice_hw *hw, u32 offset, u32 *length, u8 *data,
 					 offset, read_size,
 					 data + bytes_read, last_cmd,
 					 read_shadow_ram, NULL);
-		if (status)
-			break;
-
-		bytes_read += read_size;
-		offset += read_size;
+		if (status) {
+			if (hw->adminq.sq_last_status != LIBIE_AQ_RC_EBUSY ||
+			    retry_cnt > ICE_SQ_SEND_MAX_EXECUTE)
+				break;
+			ice_debug(hw, ICE_DBG_NVM,
+				  "NVM read EBUSY error, retry %d\n",
+				  retry_cnt + 1);
+			last_cmd = false;
+			ice_release_nvm(hw);
+			msleep(ICE_SQ_SEND_DELAY_TIME_MS);
+			status = ice_acquire_nvm(hw, ICE_RES_READ);
+			if (status)
+				break;
+			retry_cnt++;
+		} else {
+			bytes_read += read_size;
+			offset += read_size;
+			retry_cnt = 0;
+		}
 	} while (!last_cmd);
 
 	*length = bytes_read;
-- 
2.34.1