sata_mv fix mv_host_intr bug for hc_irq_cause

Remove the unwanted reads of hc_irq_cause from mv_host_intr(),
thereby removing a bug whereby we were not always reading it when needed..

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 42 insertions, 29 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index d995e0e15d87..31e42deb746f 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1818,48 +1818,61 @@ static void mv_process_crpb_entries(struct ata_port *ap, struct mv_port_priv *pp
 static int mv_host_intr(struct ata_host *host, u32 main_irq_cause)
 {
         struct mv_host_priv *hpriv = host->private_data;
-        void __iomem *mmio = hpriv->base, *hc_mmio = NULL;
-        u32 hc_irq_cause = 0;
+        void __iomem *mmio = hpriv->base, *hc_mmio;
         unsigned int handled = 0, port;
 
         for (port = 0; port < hpriv->n_ports; port++) {
                 struct ata_port *ap = host->ports[port];
                 struct mv_port_priv *pp;
-                unsigned int shift, hardport, port_cause;
-                /*
-                 * When we move to the second hc, flag our cached
-                 * copies of hc_mmio (and hc_irq_cause) as invalid again.
-                 */
-                if (port == MV_PORTS_PER_HC)
-                        hc_mmio = NULL;
-                /*
-                 * Do nothing if port is not interrupting or is disabled:
-                 */
+                unsigned int p, shift, hardport, port_cause;
+
                 MV_PORT_TO_SHIFT_AND_HARDPORT(port, shift, hardport);
-                port_cause = (main_irq_cause >> shift) & (DONE_IRQ | ERR_IRQ);
-                if (!port_cause || !ap || (ap->flags & ATA_FLAG_DISABLED))
-                        continue;
                 /*
-                 * Each hc within the host has its own hc_irq_cause register.
-                 * We defer reading it until we know we need it, right now:
-                 *
-                 * FIXME later: we don't really need to read this register
-                 * (some logic changes required below if we go that way),
-                 * because it doesn't tell us anything new.  But we do need
-                 * to write to it, outside the top of this loop,
-                 * to reset the interrupt triggers for next time.
+                 * Each hc within the host has its own hc_irq_cause register,
+                 * where the interrupting ports bits get ack'd.
                  */
-                if (!hc_mmio) {
+                if (hardport == 0) {    /* first port on this hc ? */
+                        u32 hc_cause = (main_irq_cause >> shift) & HC0_IRQ_PEND;
+                        u32 port_mask, ack_irqs;
+                        /*
+                         * Skip this entire hc if nothing pending for any ports
+                         */
+                        if (!hc_cause) {
+                                port += MV_PORTS_PER_HC - 1;
+                                continue;
+                        }
+                        /*
+                         * We don't need/want to read the hc_irq_cause register,
+                         * because doing so hurts performance, and
+                         * main_irq_cause already gives us everything we need.
+                         *
+                         * But we do have to *write* to the hc_irq_cause to ack
+                         * the ports that we are handling this time through.
+                         *
+                         * This requires that we create a bitmap for those
+                         * ports which interrupted us, and use that bitmap
+                         * to ack (only) those ports via hc_irq_cause.
+                         */
+                        ack_irqs = 0;
+                        for (p = 0; p < MV_PORTS_PER_HC; ++p) {
+                                if ((port + p) >= hpriv->n_ports)
+                                        break;
+                                port_mask = (DONE_IRQ | ERR_IRQ) << (p * 2);
+                                if (hc_cause & port_mask)
+                                        ack_irqs |= (DMA_IRQ | DEV_IRQ) << p;
+                        }
                         hc_mmio = mv_hc_base_from_port(mmio, port);
-                        hc_irq_cause = readl(hc_mmio + HC_IRQ_CAUSE_OFS);
-                        writelfl(~hc_irq_cause, hc_mmio + HC_IRQ_CAUSE_OFS);
+                        writelfl(~ack_irqs, hc_mmio + HC_IRQ_CAUSE_OFS);
                         handled = 1;
                 }
+                port_cause = (main_irq_cause >> shift) & (DONE_IRQ | ERR_IRQ);
+                if (!port_cause)
+                        continue;
                 /*
                  * Process completed CRPB response(s) before other events.
                  */
                 pp = ap->private_data;
-                if (hc_irq_cause & (DMA_IRQ << hardport)) {
+                if (port_cause & DONE_IRQ) {
                         if (pp->pp_flags & MV_PP_FLAG_EDMA_EN)
                                 mv_process_crpb_entries(ap, pp);
                 }
@@ -1868,15 +1881,15 @@ static int mv_host_intr(struct ata_host *host, u32 main_irq_cause)
                  */
                 if (unlikely(port_cause & ERR_IRQ)) {
                         mv_err_intr(ap);
-                } else if (hc_irq_cause & (DEV_IRQ << hardport)) {
+                } else {
                         if (!(pp->pp_flags & MV_PP_FLAG_EDMA_EN)) {
                                 struct ata_queued_cmd *qc = mv_get_active_qc(ap);
                                 if (qc) {
                                         ata_sff_host_intr(ap, qc);
                                         continue;
                                 }
+                                mv_unexpected_intr(ap);
                         }
-                        mv_unexpected_intr(ap);
                 }
         }
         return handled;