sata_rcar: fix interrupt handling

The driver's interrupt handling code is too picky in deciding whether it should
handle an interrupt or not which causes completely unneeded spurious interrupts.
Thus make sata_rcar_{ata|serr}_interrupt() *void*; add ATA status register read
to sata_rcar_ata_interrupt() to clear an unexpected ATA interrupt -- it doesn't
get cleared by writing to the SATAINTSTAT register in the interrupt mode we use.

Also, in sata_rcar_ata_interrupt() we should check SATAINTSTAT register only for
enabled interrupts and we should clear  only those interrupts  that we have read
as active first time around, because else we have  a  race and risk clearing  an
interrupt that  can  occur between read  and write of the  SATAINTSTAT  register
and never registering it...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

1 files changed, 11 insertions, 12 deletions

diff --git a/drivers/ata/sata_rcar.c b/drivers/ata/sata_rcar.c
index a8e091aafdde..249c8a289bfd 100644
--- a/drivers/ata/sata_rcar.c
+++ b/drivers/ata/sata_rcar.c
@@ -619,17 +619,16 @@ static struct ata_port_operations sata_rcar_port_ops = {
         .bmdma_status           = sata_rcar_bmdma_status,
 };
 
-static int sata_rcar_serr_interrupt(struct ata_port *ap)
+static void sata_rcar_serr_interrupt(struct ata_port *ap)
 {
         struct sata_rcar_priv *priv = ap->host->private_data;
         struct ata_eh_info *ehi = &ap->link.eh_info;
         int freeze = 0;
-        int handled = 0;
         u32 serror;
 
         serror = ioread32(priv->base + SCRSERR_REG);
         if (!serror)
-                return 0;
+                return;
 
         DPRINTK("SError @host_intr: 0x%x\n", serror);
 
@@ -642,7 +641,6 @@ static int sata_rcar_serr_interrupt(struct ata_port *ap)
                 ata_ehi_push_desc(ehi, "%s", "hotplug");
 
                 freeze = serror & SERR_COMM_WAKE ? 0 : 1;
-                handled = 1;
         }
 
         /* freeze or abort */
@@ -650,11 +648,9 @@ static int sata_rcar_serr_interrupt(struct ata_port *ap)
                 ata_port_freeze(ap);
         else
                 ata_port_abort(ap);
-
-        return handled;
 }
 
-static int sata_rcar_ata_interrupt(struct ata_port *ap)
+static void sata_rcar_ata_interrupt(struct ata_port *ap)
 {
         struct ata_queued_cmd *qc;
         int handled = 0;
@@ -663,7 +659,9 @@ static int sata_rcar_ata_interrupt(struct ata_port *ap)
         if (qc)
                 handled |= ata_bmdma_port_intr(ap, qc);
 
-        return handled;
+        /* be sure to clear ATA interrupt */
+        if (!handled)
+                sata_rcar_check_status(ap);
 }
 
 static irqreturn_t sata_rcar_interrupt(int irq, void *dev_instance)
@@ -678,20 +676,21 @@ static irqreturn_t sata_rcar_interrupt(int irq, void *dev_instance)
         spin_lock_irqsave(&host->lock, flags);
 
         sataintstat = ioread32(priv->base + SATAINTSTAT_REG);
+        sataintstat &= SATA_RCAR_INT_MASK;
         if (!sataintstat)
                 goto done;
         /* ack */
-        iowrite32(sataintstat & ~SATA_RCAR_INT_MASK,
-                 priv->base + SATAINTSTAT_REG);
+        iowrite32(~sataintstat & 0x7ff, priv->base + SATAINTSTAT_REG);
 
         ap = host->ports[0];
 
         if (sataintstat & SATAINTSTAT_ATA)
-                handled |= sata_rcar_ata_interrupt(ap);
+                sata_rcar_ata_interrupt(ap);
 
         if (sataintstat & SATAINTSTAT_SERR)
-                handled |= sata_rcar_serr_interrupt(ap);
+                sata_rcar_serr_interrupt(ap);
 
+        handled = 1;
 done:
         spin_unlock_irqrestore(&host->lock, flags);