[PATCH v2 3/3] scsi: aacraid: Auto detect INTx or MSIx mode during sync cmd processing

[Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>]

During sync command processing if legacy INTx status indicates
command is not completed, sample the MSIx register and check if
it indicates command completion, set controller MSIx enabled flag.

Signed-off-by: Prasad B Munirathnam <prasad.munirathnam@microsemi.com>
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Reviewed-by: Dave Carroll <david.carroll@microsemi.com>

---
Changes in V2:
Re based on Linus Master

 drivers/scsi/aacraid/aacraid.h |  1 +
 drivers/scsi/aacraid/src.c     | 22 ++++++++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/aacraid/aacraid.h b/drivers/scsi/aacraid/aacraid.h
index c3fdec9..29bf1e6 100644
--- a/drivers/scsi/aacraid/aacraid.h
+++ b/drivers/scsi/aacraid/aacraid.h
@@ -1231,6 +1231,7 @@ struct src_registers {
 
 #define SRC_ODR_SHIFT		12
 #define SRC_IDR_SHIFT		9
+#define SRC_MSI_READ_MASK	0x1000
 
 typedef void (*fib_callback)(void *ctxt, struct fib *fibctx);
 
diff --git a/drivers/scsi/aacraid/src.c b/drivers/scsi/aacraid/src.c
index 09b82d3..3122389f 100644
--- a/drivers/scsi/aacraid/src.c
+++ b/drivers/scsi/aacraid/src.c
@@ -1405,13 +1405,23 @@ void aac_src_access_devreg(struct aac_dev *dev, int mode)
 
 static int aac_src_get_sync_status(struct aac_dev *dev)
 {
+	int msix_val = 0;
+	int legacy_val = 0;
 
-	int val;
+	msix_val = src_readl(dev, MUnit.ODR_MSI) & SRC_MSI_READ_MASK ? 1 : 0;
 
-	if (dev->msi_enabled)
-		val = src_readl(dev, MUnit.ODR_MSI) & 0x1000 ? 1 : 0;
-	else
-		val = src_readl(dev, MUnit.ODR_R) >> SRC_ODR_SHIFT;
+	if (!dev->msi_enabled) {
+		/*
+		 * if Legacy int status indicates cmd is not complete
+		 * sample MSIx register to see if it indiactes cmd complete,
+		 * if yes set the controller in MSIx mode and consider cmd
+		 * completed
+		 */
+		legacy_val = src_readl(dev, MUnit.ODR_R) >> SRC_ODR_SHIFT;
+		if (!(legacy_val & 1) && msix_val)
+			dev->msi_enabled = 1;
+		return legacy_val;
+	}
 
-	return val;
+	return msix_val;
 }
-- 
2.9.4