sata_rcar: fix interrupt handling

commit 52a2a1087b5924de00484f35ef5e2a73f61dbd22 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/ata/sata_rcar.c b/drivers/ata/sata_rcar.c
index 14a8c738f3177507a86f2c983e55dba9512255ae..d7b77e02b10029d57b9a36567c903bdf476ec10b 100644 (file)
--- a/drivers/ata/sata_rcar.c
+++ b/drivers/ata/sata_rcar.c
@@ -618,17 +618,16 @@ 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);
 
@@ -641,7 +640,6 @@ 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 */
@@ -649,11 +647,9 @@ 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;
@@ -662,7 +658,9 @@ 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)
@@ -677,20 +675,21 @@ 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);