sata_mv ncq Introduce per-tag SG tables

In preparation for supporting NCQ, we must allocate separate SG tables
for each command tag, rather than just a single table per port as before.

Gen-I hardware cannot do NCQ, though, so we still allocate just a single
table for that, but populate it in all 32 slots to avoid special-cases
elsewhere in hotter paths of the code.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 40 insertions, 15 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 1c53c8a7d21f..ea7af1f16844 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -398,8 +398,8 @@ struct mv_port_priv {
         dma_addr_t              crqb_dma;
         struct mv_crpb          *crpb;
         dma_addr_t              crpb_dma;
-        struct mv_sg            *sg_tbl;
-        dma_addr_t              sg_tbl_dma;
+        struct mv_sg            *sg_tbl[MV_MAX_Q_DEPTH];
+        dma_addr_t              sg_tbl_dma[MV_MAX_Q_DEPTH];
 
         unsigned int            req_idx;
         unsigned int            resp_idx;
@@ -483,6 +483,10 @@ static void mv_edma_cfg(struct mv_port_priv *pp, struct mv_host_priv *hpriv,
                         void __iomem *port_mmio, int want_ncq);
 static int __mv_stop_dma(struct ata_port *ap);
 
+/* .sg_tablesize is (MV_MAX_SG_CT / 2) in the structures below
+ * because we have to allow room for worst case splitting of
+ * PRDs for 64K boundaries in mv_fill_sg().
+ */
 static struct scsi_host_template mv5_sht = {
         .module                 = THIS_MODULE,
         .name                   = DRV_NAME,
@@ -1107,6 +1111,7 @@ static void mv_port_free_dma_mem(struct ata_port *ap)
 {
         struct mv_host_priv *hpriv = ap->host->private_data;
         struct mv_port_priv *pp = ap->private_data;
+        int tag;
 
         if (pp->crqb) {
                 dma_pool_free(hpriv->crqb_pool, pp->crqb, pp->crqb_dma);
@@ -1116,9 +1121,18 @@ static void mv_port_free_dma_mem(struct ata_port *ap)
                 dma_pool_free(hpriv->crpb_pool, pp->crpb, pp->crpb_dma);
                 pp->crpb = NULL;
         }
-        if (pp->sg_tbl) {
-                dma_pool_free(hpriv->sg_tbl_pool, pp->sg_tbl, pp->sg_tbl_dma);
-                pp->sg_tbl = NULL;
+        /*
+         * For GEN_I, there's no NCQ, so we have only a single sg_tbl.
+         * For later hardware, we have one unique sg_tbl per NCQ tag.
+         */
+        for (tag = 0; tag < MV_MAX_Q_DEPTH; ++tag) {
+                if (pp->sg_tbl[tag]) {
+                        if (tag == 0 || !IS_GEN_I(hpriv))
+                                dma_pool_free(hpriv->sg_tbl_pool,
+                                              pp->sg_tbl[tag],
+                                              pp->sg_tbl_dma[tag]);
+                        pp->sg_tbl[tag] = NULL;
+                }
         }
 }
 
@@ -1139,7 +1153,7 @@ static int mv_port_start(struct ata_port *ap)
         struct mv_port_priv *pp;
         void __iomem *port_mmio = mv_ap_base(ap);
         unsigned long flags;
-        int rc;
+        int tag, rc;
 
         pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
         if (!pp)
@@ -1160,10 +1174,21 @@ static int mv_port_start(struct ata_port *ap)
                 goto out_port_free_dma_mem;
         memset(pp->crpb, 0, MV_CRPB_Q_SZ);
 
-        pp->sg_tbl = dma_pool_alloc(hpriv->sg_tbl_pool, GFP_KERNEL,
-                                                              &pp->sg_tbl_dma);
-        if (!pp->sg_tbl)
-                goto out_port_free_dma_mem;
+        /*
+         * For GEN_I, there's no NCQ, so we only allocate a single sg_tbl.
+         * For later hardware, we need one unique sg_tbl per NCQ tag.
+         */
+        for (tag = 0; tag < MV_MAX_Q_DEPTH; ++tag) {
+                if (tag == 0 || !IS_GEN_I(hpriv)) {
+                        pp->sg_tbl[tag] = dma_pool_alloc(hpriv->sg_tbl_pool,
+                                              GFP_KERNEL, &pp->sg_tbl_dma[tag]);
+                        if (!pp->sg_tbl[tag])
+                                goto out_port_free_dma_mem;
+                } else {
+                        pp->sg_tbl[tag]     = pp->sg_tbl[0];
+                        pp->sg_tbl_dma[tag] = pp->sg_tbl_dma[0];
+                }
+        }
 
         spin_lock_irqsave(&ap->host->lock, flags);
 
@@ -1214,7 +1239,7 @@ static void mv_fill_sg(struct ata_queued_cmd *qc)
         struct mv_sg *mv_sg, *last_sg = NULL;
         unsigned int si;
 
-        mv_sg = pp->sg_tbl;
+        mv_sg = pp->sg_tbl[qc->tag];
         for_each_sg(qc->sg, sg, qc->n_elem, si) {
                 dma_addr_t addr = sg_dma_address(sg);
                 u32 sg_len = sg_dma_len(sg);
@@ -1284,9 +1309,9 @@ static void mv_qc_prep(struct ata_queued_cmd *qc)
         in_index = pp->req_idx & MV_MAX_Q_DEPTH_MASK;
 
         pp->crqb[in_index].sg_addr =
-                cpu_to_le32(pp->sg_tbl_dma & 0xffffffff);
+                cpu_to_le32(pp->sg_tbl_dma[qc->tag] & 0xffffffff);
         pp->crqb[in_index].sg_addr_hi =
-                cpu_to_le32((pp->sg_tbl_dma >> 16) >> 16);
+                cpu_to_le32((pp->sg_tbl_dma[qc->tag] >> 16) >> 16);
         pp->crqb[in_index].ctrl_flags = cpu_to_le16(flags);
 
         cw = &pp->crqb[in_index].ata_cmd[0];
@@ -1377,8 +1402,8 @@ static void mv_qc_prep_iie(struct ata_queued_cmd *qc)
         in_index = pp->req_idx & MV_MAX_Q_DEPTH_MASK;
 
         crqb = (struct mv_crqb_iie *) &pp->crqb[in_index];
-        crqb->addr = cpu_to_le32(pp->sg_tbl_dma & 0xffffffff);
-        crqb->addr_hi = cpu_to_le32((pp->sg_tbl_dma >> 16) >> 16);
+        crqb->addr = cpu_to_le32(pp->sg_tbl_dma[qc->tag] & 0xffffffff);
+        crqb->addr_hi = cpu_to_le32((pp->sg_tbl_dma[qc->tag] >> 16) >> 16);
         crqb->flags = cpu_to_le32(flags);
 
         tf = &qc->tf;