sata_sil: fix spurious IRQ handling

Interestingly, sata_sil raises spurious interrupts if it's coupled
with Sil SATA_PATA bridge.  Currently, sata_sil interrupt handler is
strict about spurious interrupts and freezes the port when it occurs.
This patch makes it more forgiving.

* On SATA PHY event interrupt, serror value is checked to see whether
  it really is PHYRDY CHG event.  If not, SATA PHY event interrupt is
  ignored.

* If ATA interrupt occurs while no command is in progress, it's
  cleared and ignored.

This fixes bugzilla bug 9505.

  http://bugzilla.kernel.org/show_bug.cgi?id=9505

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/ata/sata_sil.c b/drivers/ata/sata_sil.c
index 4e6e381279cc..025622b14efb 100644
--- a/drivers/ata/sata_sil.c
+++ b/drivers/ata/sata_sil.c
@@ -390,23 +390,28 @@ static void sil_host_intr(struct ata_port *ap, u32 bmdma2)
                 sil_scr_read(ap, SCR_ERROR, &serror);
                 sil_scr_write(ap, SCR_ERROR, serror);
 
-                /* Trigger hotplug and accumulate SError only if the
-                 * port isn't already frozen.  Otherwise, PHY events
-                 * during hardreset makes controllers with broken SIEN
-                 * repeat probing needlessly.
+                /* Sometimes spurious interrupts occur, double check
+                 * it's PHYRDY CHG.
                  */
-                if (!(ap->pflags & ATA_PFLAG_FROZEN)) {
-                        ata_ehi_hotplugged(&ap->link.eh_info);
-                        ap->link.eh_info.serror |= serror;
+                if (serror & SERR_PHYRDY_CHG) {
+                        /* Trigger hotplug and accumulate SError only
+                         * if the port isn't already frozen.
+                         * Otherwise, PHY events during hardreset
+                         * makes controllers with broken SIEN repeat
+                         * probing needlessly.
+                         */
+                        if (!(ap->pflags & ATA_PFLAG_FROZEN)) {
+                                ata_ehi_hotplugged(&ap->link.eh_info);
+                                ap->link.eh_info.serror |= serror;
+                        }
+                        goto freeze;
                 }
 
-                goto freeze;
+                if (!(bmdma2 & SIL_DMA_COMPLETE))
+                        return;
         }
 
-        if (unlikely(!qc))
-                goto freeze;
-
-        if (unlikely(qc->tf.flags & ATA_TFLAG_POLLING)) {
+        if (unlikely(!qc || (qc->tf.flags & ATA_TFLAG_POLLING))) {
                 /* this sometimes happens, just clear IRQ */
                 ata_chk_status(ap);
                 return;