[PATCH v4 1/2] mpt3sas: Perform additional retries if Doorbell read returns 0

[Ranjan Kumar <ranjan.kumar@broadcom.com>]

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The driver retries certain register reads for 3 times if the
returned value is 0, this was done based on hardware specification
where the controller could possibly return 0 for certain registers
when there is a parallel access to some of other registers from the
firmware due to BMC out of band interactions.Recently it is observed
that in certain systems with increased BMC interactions, the values
returned are 0 even for 3 retries (the proper value is returned
between 4 to 6 retries).Hence this patch changes the retry
count 3 to 30, which is a revised recommendation, to avoid
the out of band conflict.

Fixes: b899202901a8 ("mpt3sas: Add separate function for aero doorbell reads")
Cc: stable@vger.kernel.org
Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
---
 drivers/scsi/mpt3sas/mpt3sas_base.c | 46 +++++++++++++++++++++--------
 drivers/scsi/mpt3sas/mpt3sas_base.h |  1 +
 2 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 53f5492579cb..5284584e4cd2 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -138,6 +138,9 @@ _base_get_ioc_facts(struct MPT3SAS_ADAPTER *ioc);
 static void
 _base_clear_outstanding_commands(struct MPT3SAS_ADAPTER *ioc);
 
+static u32
+_base_readl_ext_retry(const volatile void __iomem *addr);
+
 /**
  * mpt3sas_base_check_cmd_timeout - Function
  *		to check timeout and command termination due
@@ -213,6 +216,20 @@ _base_readl_aero(const volatile void __iomem *addr)
 	return ret_val;
 }
 
+static u32
+_base_readl_ext_retry(const volatile void __iomem *addr)
+{
+	u32 i, ret_val;
+
+	for (i = 0 ; i < 30 ; i++) {
+		ret_val = readl(addr);
+		if (ret_val == 0)
+			continue;
+	}
+
+	return ret_val;
+}
+
 static inline u32
 _base_readl(const volatile void __iomem *addr)
 {
@@ -940,7 +957,7 @@ mpt3sas_halt_firmware(struct MPT3SAS_ADAPTER *ioc)
 
 	dump_stack();
 
-	doorbell = ioc->base_readl(&ioc->chip->Doorbell);
+	doorbell = ioc->base_readl_ext_retry(&ioc->chip->Doorbell);
 	if ((doorbell & MPI2_IOC_STATE_MASK) == MPI2_IOC_STATE_FAULT) {
 		mpt3sas_print_fault_code(ioc, doorbell &
 		    MPI2_DOORBELL_DATA_MASK);
@@ -6686,7 +6703,7 @@ mpt3sas_base_get_iocstate(struct MPT3SAS_ADAPTER *ioc, int cooked)
 {
 	u32 s, sc;
 
-	s = ioc->base_readl(&ioc->chip->Doorbell);
+	s = ioc->base_readl_ext_retry(&ioc->chip->Doorbell);
 	sc = s & MPI2_IOC_STATE_MASK;
 	return cooked ? sc : s;
 }
@@ -6831,7 +6848,7 @@ _base_wait_for_doorbell_ack(struct MPT3SAS_ADAPTER *ioc, int timeout)
 					   __func__, count, timeout));
 			return 0;
 		} else if (int_status & MPI2_HIS_IOC2SYS_DB_STATUS) {
-			doorbell = ioc->base_readl(&ioc->chip->Doorbell);
+			doorbell = ioc->base_readl_ext_retry(&ioc->chip->Doorbell);
 			if ((doorbell & MPI2_IOC_STATE_MASK) ==
 			    MPI2_IOC_STATE_FAULT) {
 				mpt3sas_print_fault_code(ioc, doorbell);
@@ -6871,7 +6888,7 @@ _base_wait_for_doorbell_not_used(struct MPT3SAS_ADAPTER *ioc, int timeout)
 	count = 0;
 	cntdn = 1000 * timeout;
 	do {
-		doorbell_reg = ioc->base_readl(&ioc->chip->Doorbell);
+		doorbell_reg = ioc->base_readl_ext_retry(&ioc->chip->Doorbell);
 		if (!(doorbell_reg & MPI2_DOORBELL_USED)) {
 			dhsprintk(ioc,
 				  ioc_info(ioc, "%s: successful count(%d), timeout(%d)\n",
@@ -7019,7 +7036,7 @@ _base_handshake_req_reply_wait(struct MPT3SAS_ADAPTER *ioc, int request_bytes,
 	__le32 *mfp;
 
 	/* make sure doorbell is not in use */
-	if ((ioc->base_readl(&ioc->chip->Doorbell) & MPI2_DOORBELL_USED)) {
+	if ((ioc->base_readl_ext_retry(&ioc->chip->Doorbell) & MPI2_DOORBELL_USED)) {
 		ioc_err(ioc, "doorbell is in use (line=%d)\n", __LINE__);
 		return -EFAULT;
 	}
@@ -7068,7 +7085,7 @@ _base_handshake_req_reply_wait(struct MPT3SAS_ADAPTER *ioc, int request_bytes,
 	}
 
 	/* read the first two 16-bits, it gives the total length of the reply */
-	reply[0] = le16_to_cpu(ioc->base_readl(&ioc->chip->Doorbell)
+	reply[0] = le16_to_cpu(ioc->base_readl_ext_retry(&ioc->chip->Doorbell)
 	    & MPI2_DOORBELL_DATA_MASK);
 	writel(0, &ioc->chip->HostInterruptStatus);
 	if ((_base_wait_for_doorbell_int(ioc, 5))) {
@@ -7076,7 +7093,7 @@ _base_handshake_req_reply_wait(struct MPT3SAS_ADAPTER *ioc, int request_bytes,
 			__LINE__);
 		return -EFAULT;
 	}
-	reply[1] = le16_to_cpu(ioc->base_readl(&ioc->chip->Doorbell)
+	reply[1] = le16_to_cpu(ioc->base_readl_ext_retry(&ioc->chip->Doorbell)
 	    & MPI2_DOORBELL_DATA_MASK);
 	writel(0, &ioc->chip->HostInterruptStatus);
 
@@ -7087,10 +7104,10 @@ _base_handshake_req_reply_wait(struct MPT3SAS_ADAPTER *ioc, int request_bytes,
 			return -EFAULT;
 		}
 		if (i >=  reply_bytes/2) /* overflow case */
-			ioc->base_readl(&ioc->chip->Doorbell);
+			ioc->base_readl_ext_retry(&ioc->chip->Doorbell);
 		else
 			reply[i] = le16_to_cpu(
-			    ioc->base_readl(&ioc->chip->Doorbell)
+			    ioc->base_readl_ext_retry(&ioc->chip->Doorbell)
 			    & MPI2_DOORBELL_DATA_MASK);
 		writel(0, &ioc->chip->HostInterruptStatus);
 	}
@@ -7949,7 +7966,7 @@ _base_diag_reset(struct MPT3SAS_ADAPTER *ioc)
 			goto out;
 		}
 
-		host_diagnostic = ioc->base_readl(&ioc->chip->HostDiagnostic);
+		host_diagnostic = ioc->base_readl_ext_retry(&ioc->chip->HostDiagnostic);
 		drsprintk(ioc,
 			  ioc_info(ioc, "wrote magic sequence: count(%d), host_diagnostic(0x%08x)\n",
 				   count, host_diagnostic));
@@ -7969,7 +7986,7 @@ _base_diag_reset(struct MPT3SAS_ADAPTER *ioc)
 	for (count = 0; count < (300000000 /
 		MPI2_HARD_RESET_PCIE_SECOND_READ_DELAY_MICRO_SEC); count++) {
 
-		host_diagnostic = ioc->base_readl(&ioc->chip->HostDiagnostic);
+		host_diagnostic = ioc->base_readl_ext_retry(&ioc->chip->HostDiagnostic);
 
 		if (host_diagnostic == 0xFFFFFFFF) {
 			ioc_info(ioc,
@@ -8359,10 +8376,13 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
 	ioc->rdpq_array_enable_assigned = 0;
 	ioc->use_32bit_dma = false;
 	ioc->dma_mask = 64;
-	if (ioc->is_aero_ioc)
+	if (ioc->is_aero_ioc) {
 		ioc->base_readl = &_base_readl_aero;
-	else
+		ioc->base_readl_ext_retry = &_base_readl_ext_retry;
+	} else {
 		ioc->base_readl = &_base_readl;
+		ioc->base_readl_ext_retry = &_base_readl;
+	}
 	r = mpt3sas_base_map_resources(ioc);
 	if (r)
 		goto out_free_resources;
diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.h b/drivers/scsi/mpt3sas/mpt3sas_base.h
index 05364aa15ecd..10055c7e4a9f 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.h
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.h
@@ -1618,6 +1618,7 @@ struct MPT3SAS_ADAPTER {
 	u8		diag_trigger_active;
 	u8		atomic_desc_capable;
 	BASE_READ_REG	base_readl;
+	BASE_READ_REG	base_readl_ext_retry;
 	struct SL_WH_MASTER_TRIGGER_T diag_trigger_master;
 	struct SL_WH_EVENT_TRIGGERS_T diag_trigger_event;
 	struct SL_WH_SCSI_TRIGGERS_T diag_trigger_scsi;
-- 
2.31.1


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