scsi: megaraid_sas: Increase register read retry rount from 3 to 30 for selected registers

In BMC environments with concurrent access to multiple registers, certain
registers occasionally yield a value of 0 even after 3 retries due to
hardware errata. As a fix, we have extended the retry count from 3 to 30.

The same errata applies to the mpt3sas driver, and a similar patch has
been accepted. Please find more details in the mpt3sas patch reference
link.

Link: https://lore.kernel.org/r/[email protected]
Fixes: 272652f ("scsi: megaraid_sas: add retry logic in megasas_readl")
Cc: [email protected]
Signed-off-by: Chandrakanth patil <[email protected]>
Signed-off-by: Sumit Saxena <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

Author: cp890582

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -263,13 +263,13 @@ u32 megasas_readl(struct megasas_instance *instance,
 	 * Fusion registers could intermittently return all zeroes.
 	 * This behavior is transient in nature and subsequent reads will
 	 * return valid value. As a workaround in driver, retry readl for
-	 * upto three times until a non-zero value is read.
+	 * up to thirty times until a non-zero value is read.
 	 */
 	if (instance->adapter_type == AERO_SERIES) {
 		do {
 			ret_val = readl(addr);
 			i++;
-		} while (ret_val == 0 && i < 3);
+		} while (ret_val == 0 && i < 30);
 		return ret_val;
 	} else {
 		return readl(addr);