sata_mv: simplify request/response queue handling

Try and simplify handling of the request/response queues.

Maintain the cached copies of queue indexes in a fully-masked state,
rather than having each use of them have to do the masking.

Split off handling of a single crpb response into a separate function,
to reduce complexity in the main mv_process_crpb_entries() routine.

Ignore the rarely-valid error bits from the crpb status field,
as we already handle that information in mv_err_intr().

For now, preserve the rest of the original logic.
A later patch will deal with fixing that separately.

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

1 files changed, 56 insertions, 53 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 552006853cd7..cee78f9e9d1b 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -804,7 +804,8 @@ static void mv_set_edma_ptrs(void __iomem *port_mmio,
         /*
          * initialize request queue
          */
-        index = (pp->req_idx & MV_MAX_Q_DEPTH_MASK) << EDMA_REQ_Q_PTR_SHIFT;
+        pp->req_idx &= MV_MAX_Q_DEPTH_MASK;     /* paranoia */
+        index = pp->req_idx << EDMA_REQ_Q_PTR_SHIFT;
 
         WARN_ON(pp->crqb_dma & 0x3ff);
         writel((pp->crqb_dma >> 16) >> 16, port_mmio + EDMA_REQ_Q_BASE_HI_OFS);
@@ -820,7 +821,8 @@ static void mv_set_edma_ptrs(void __iomem *port_mmio,
         /*
          * initialize response queue
          */
-        index = (pp->resp_idx & MV_MAX_Q_DEPTH_MASK) << EDMA_RSP_Q_PTR_SHIFT;
+        pp->resp_idx &= MV_MAX_Q_DEPTH_MASK;    /* paranoia */
+        index = pp->resp_idx << EDMA_RSP_Q_PTR_SHIFT;
 
         WARN_ON(pp->crpb_dma & 0xff);
         writel((pp->crpb_dma >> 16) >> 16, port_mmio + EDMA_RSP_Q_BASE_HI_OFS);
@@ -1312,7 +1314,7 @@ static void mv_qc_prep(struct ata_queued_cmd *qc)
         flags |= (qc->dev->link->pmp & 0xf) << CRQB_PMP_SHIFT;
 
         /* get current queue index from software */
-        in_index = pp->req_idx & MV_MAX_Q_DEPTH_MASK;
+        in_index = pp->req_idx;
 
         pp->crqb[in_index].sg_addr =
                 cpu_to_le32(pp->sg_tbl_dma[qc->tag] & 0xffffffff);
@@ -1404,7 +1406,7 @@ static void mv_qc_prep_iie(struct ata_queued_cmd *qc)
         flags |= (qc->dev->link->pmp & 0xf) << CRQB_PMP_SHIFT;
 
         /* get current queue index from software */
-        in_index = pp->req_idx & MV_MAX_Q_DEPTH_MASK;
+        in_index = pp->req_idx;
 
         crqb = (struct mv_crqb_iie *) &pp->crqb[in_index];
         crqb->addr = cpu_to_le32(pp->sg_tbl_dma[qc->tag] & 0xffffffff);
@@ -1471,9 +1473,8 @@ static unsigned int mv_qc_issue(struct ata_queued_cmd *qc)
 
         mv_start_dma(ap, port_mmio, pp, qc->tf.protocol);
 
-        pp->req_idx++;
-
-        in_index = (pp->req_idx & MV_MAX_Q_DEPTH_MASK) << EDMA_REQ_Q_PTR_SHIFT;
+        pp->req_idx = (pp->req_idx + 1) & MV_MAX_Q_DEPTH_MASK;
+        in_index = pp->req_idx << EDMA_REQ_Q_PTR_SHIFT;
 
         /* and write the request in pointer to kick the EDMA to life */
         writelfl((pp->crqb_dma & EDMA_REQ_Q_BASE_LO_MASK) | in_index,
@@ -1607,70 +1608,72 @@ static void mv_intr_pio(struct ata_port *ap)
         ata_qc_complete(qc);
 }
 
-static void mv_intr_edma(struct ata_port *ap)
+static void mv_process_crpb_response(struct ata_port *ap,
+                struct mv_crpb *response, unsigned int tag, int ncq_enabled)
+{
+        struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
+
+        if (qc) {
+                u8 ata_status;
+                u16 edma_status = le16_to_cpu(response->flags);
+                /*
+                 * edma_status from a response queue entry:
+                 *   LSB is from EDMA_ERR_IRQ_CAUSE_OFS (non-NCQ only).
+                 *   MSB is saved ATA status from command completion.
+                 */
+                if (!ncq_enabled) {
+                        u8 err_cause = edma_status & 0xff & ~EDMA_ERR_DEV;
+                        if (err_cause) {
+                                /*
+                                 * Error will be seen/handled by mv_err_intr().
+                                 * So do nothing at all here.
+                                 */
+                                return;
+                        }
+                }
+                ata_status = edma_status >> CRPB_FLAG_STATUS_SHIFT;
+                qc->err_mask |= ac_err_mask(ata_status);
+                ata_qc_complete(qc);
+        } else {
+                ata_port_printk(ap, KERN_ERR, "%s: no qc for tag=%d\n",
+                                __func__, tag);
+        }
+}
+
+static void mv_process_crpb_entries(struct ata_port *ap, struct mv_port_priv *pp)
 {
         void __iomem *port_mmio = mv_ap_base(ap);
         struct mv_host_priv *hpriv = ap->host->private_data;
-        struct mv_port_priv *pp = ap->private_data;
-        struct ata_queued_cmd *qc;
-        u32 out_index, in_index;
+        u32 in_index;
         bool work_done = false;
+        int ncq_enabled = (pp->pp_flags & MV_PP_FLAG_NCQ_EN);
 
-        /* get h/w response queue pointer */
+        /* Get the hardware queue position index */
         in_index = (readl(port_mmio + EDMA_RSP_Q_IN_PTR_OFS)
                         >> EDMA_RSP_Q_PTR_SHIFT) & MV_MAX_Q_DEPTH_MASK;
 
-        while (1) {
-                u16 status;
+        /* Process new responses from since the last time we looked */
+        while (in_index != pp->resp_idx) {
                 unsigned int tag;
+                struct mv_crpb *response = &pp->crpb[pp->resp_idx];
 
-                /* get s/w response queue last-read pointer, and compare */
-                out_index = pp->resp_idx & MV_MAX_Q_DEPTH_MASK;
-                if (in_index == out_index)
-                        break;
+                pp->resp_idx = (pp->resp_idx + 1) & MV_MAX_Q_DEPTH_MASK;
 
-                /* 50xx: get active ATA command */
-                if (IS_GEN_I(hpriv))
+                if (IS_GEN_I(hpriv)) {
+                        /* 50xx: no NCQ, only one command active at a time */
                         tag = ap->link.active_tag;
-
-                /* Gen II/IIE: get active ATA command via tag, to enable
-                 * support for queueing.  this works transparently for
-                 * queued and non-queued modes.
-                 */
-                else
-                        tag = le16_to_cpu(pp->crpb[out_index].id) & 0x1f;
-
-                qc = ata_qc_from_tag(ap, tag);
-
-                /* For non-NCQ mode, the lower 8 bits of status
-                 * are from EDMA_ERR_IRQ_CAUSE_OFS,
-                 * which should be zero if all went well.
-                 */
-                status = le16_to_cpu(pp->crpb[out_index].flags);
-                if ((status & 0xff) && !(pp->pp_flags & MV_PP_FLAG_NCQ_EN)) {
-                        mv_err_intr(ap, qc);
-                        return;
-                }
-
-                /* and finally, complete the ATA command */
-                if (qc) {
-                        qc->err_mask |=
-                                ac_err_mask(status >> CRPB_FLAG_STATUS_SHIFT);
-                        ata_qc_complete(qc);
+                } else {
+                        /* Gen II/IIE: get command tag from CRPB entry */
+                        tag = le16_to_cpu(response->id) & 0x1f;
                 }
-
-                /* advance software response queue pointer, to
-                 * indicate (after the loop completes) to hardware
-                 * that we have consumed a response queue entry.
-                 */
+                mv_process_crpb_response(ap, response, tag, ncq_enabled);
                 work_done = true;
-                pp->resp_idx++;
         }
 
         /* Update the software queue position index in hardware */
         if (work_done)
                 writelfl((pp->crpb_dma & EDMA_RSP_Q_BASE_LO_MASK) |
-                         (out_index << EDMA_RSP_Q_PTR_SHIFT),
+                         (pp->resp_idx << EDMA_RSP_Q_PTR_SHIFT),
                          port_mmio + EDMA_RSP_Q_OUT_PTR_OFS);
 }
 
@@ -1748,7 +1751,7 @@ static void mv_host_intr(struct ata_host *host, u32 relevant, unsigned int hc)
 
                 if (pp->pp_flags & MV_PP_FLAG_EDMA_EN) {
                         if ((DMA_IRQ << hardport) & hc_irq_cause)
-                                mv_intr_edma(ap);
+                                mv_process_crpb_entries(ap, pp);
                 } else {
                         if ((DEV_IRQ << hardport) & hc_irq_cause)
                                 mv_intr_pio(ap);