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/20230829090020.5417-2-ranjan.kumar@broadcom.com Fixes: 272652fcbf1a ("scsi: megaraid_sas: add retry logic in megasas_readl") Cc: stable@vger.kernel.org Signed-off-by: Chandrakanth patil chandrakanth.patil@broadcom.com Signed-off-by: Sumit Saxena sumit.saxena@broadcom.com --- drivers/scsi/megaraid/megaraid_sas_base.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c index e1aa667dae66..3d4f13da1ae8 100644 --- a/drivers/scsi/megaraid/megaraid_sas_base.c +++ b/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);