sata_mv: msi masking fix (v2)

Enable reliable use of Message-Signaled Interrupts (MSI) in sata_mv
by masking further chip interrupts within the main interrupt handler.

Based upon a suggestion by Grant Grundler.
MSI is working reliably in all of my test systems here now.

Signed-off-by: Mark Lord <mlord@pobox.com>
Reviewed-by: Grant Grundler <grundler@google.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 9e9fb9594781..f2d8a020ea53 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -33,8 +33,6 @@
  *
  * --> ATAPI support (Marvell claims the 60xx/70xx chips can do it).
  *
- * --> Investigate problems with PCI Message Signalled Interrupts (MSI).
- *
  * --> Develop a low-power-consumption strategy, and implement it.
  *
  * --> [Experiment, low priority] Investigate interrupt coalescing.
@@ -70,7 +68,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME        "sata_mv"
-#define DRV_VERSION     "1.24"
+#define DRV_VERSION     "1.25"
 
 enum {
         /* BAR's are enumerated in terms of pci_resource_start() terms */
@@ -2199,9 +2197,15 @@ static irqreturn_t mv_interrupt(int irq, void *dev_instance)
         struct ata_host *host = dev_instance;
         struct mv_host_priv *hpriv = host->private_data;
         unsigned int handled = 0;
+        int using_msi = hpriv->hp_flags & MV_HP_FLAG_MSI;
         u32 main_irq_cause, pending_irqs;
 
         spin_lock(&host->lock);
+
+        /* for MSI:  block new interrupts while in here */
+        if (using_msi)
+                writel(0, hpriv->main_irq_mask_addr);
+
         main_irq_cause = readl(hpriv->main_irq_cause_addr);
         pending_irqs   = main_irq_cause & hpriv->main_irq_mask;
         /*
@@ -2215,6 +2219,11 @@ static irqreturn_t mv_interrupt(int irq, void *dev_instance)
                         handled = mv_host_intr(host, pending_irqs);
         }
         spin_unlock(&host->lock);
+
+        /* for MSI: unmask; interrupt cause bits will retrigger now */
+        if (using_msi)
+                writel(hpriv->main_irq_mask, hpriv->main_irq_mask_addr);
+
         return IRQ_RETVAL(handled);
 }
 
@@ -3417,9 +3426,9 @@ static int mv_pci_init_one(struct pci_dev *pdev,
         if (rc)
                 return rc;
 
-        /* Enable interrupts */
-        if (msi && pci_enable_msi(pdev))
-                pci_intx(pdev, 1);
+        /* Enable message-switched interrupts, if requested */
+        if (msi && pci_enable_msi(pdev) == 0)
+                hpriv->hp_flags |= MV_HP_FLAG_MSI;
 
         mv_dump_pci_cfg(pdev, 0x68);
         mv_print_info(host);