sata_mv: optimize IRQ coalescing for 8-port chips

Enable use of the "all ports" IRQ coalescing optimization
for GEN_II / GEN_IIE chips that have dual host-controllers (8-ports).
Currently only the 6081 chip qualifies, but other chips may come along someday.

Rather than each half of the chip having to satisfy a local set of coalescing thresholds,
use of this feature groups all ports together under a single set of thresholds.

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

1 files changed, 18 insertions, 14 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index ef385451ffd5..47184567248d 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1016,7 +1016,7 @@ static void mv_set_irq_coalescing(struct ata_host *host,
         void __iomem *mmio = hpriv->base, *hc_mmio;
         u32 coal_enable = 0;
         unsigned long flags;
-        unsigned int clks;
+        unsigned int clks, is_dual_hc = hpriv->n_ports > MV_PORTS_PER_HC;
         const u32 coal_disable = PORTS_0_3_COAL_DONE | PORTS_4_7_COAL_DONE |
                                                         ALL_PORTS_COAL_DONE;
 
@@ -1033,37 +1033,41 @@ static void mv_set_irq_coalescing(struct ata_host *host,
         }
 
         spin_lock_irqsave(&host->lock, flags);
+        mv_set_main_irq_mask(host, coal_disable, 0);
 
-#if 0 /* disabled pending functional clarification from Marvell */
-        if (!IS_GEN_I(hpriv)) {
+        if (is_dual_hc && !IS_GEN_I(hpriv)) {
                 /*
-                 * GEN_II/GEN_IIE: global thresholds for the entire chip.
+                 * GEN_II/GEN_IIE with dual host controllers:
+                 * one set of global thresholds for the entire chip.
                  */
                 writel(clks,  mmio + MV_IRQ_COAL_TIME_THRESHOLD);
                 writel(count, mmio + MV_IRQ_COAL_IO_THRESHOLD);
                 /* clear leftover coal IRQ bit */
-                writelfl(~ALL_PORTS_COAL_IRQ, mmio + MV_IRQ_COAL_CAUSE);
-                clks = count = 0; /* so as to clear the alternate regs below */
-                coal_enable = ALL_PORTS_COAL_DONE;
+                writel(~ALL_PORTS_COAL_IRQ, mmio + MV_IRQ_COAL_CAUSE);
+                if (count)
+                        coal_enable = ALL_PORTS_COAL_DONE;
+                clks = count = 0; /* force clearing of regular regs below */
         }
-#endif
+
         /*
          * All chips: independent thresholds for each HC on the chip.
          */
         hc_mmio = mv_hc_base_from_port(mmio, 0);
         writel(clks,  hc_mmio + HC_IRQ_COAL_TIME_THRESHOLD_OFS);
         writel(count, hc_mmio + HC_IRQ_COAL_IO_THRESHOLD_OFS);
-        coal_enable |= PORTS_0_3_COAL_DONE;
-        if (hpriv->n_ports > 4) {
+        writel(~HC_COAL_IRQ, hc_mmio + HC_IRQ_CAUSE_OFS);
+        if (count)
+                coal_enable |= PORTS_0_3_COAL_DONE;
+        if (is_dual_hc) {
                 hc_mmio = mv_hc_base_from_port(mmio, MV_PORTS_PER_HC);
                 writel(clks,  hc_mmio + HC_IRQ_COAL_TIME_THRESHOLD_OFS);
                 writel(count, hc_mmio + HC_IRQ_COAL_IO_THRESHOLD_OFS);
-                coal_enable |= PORTS_4_7_COAL_DONE;
+                writel(~HC_COAL_IRQ, hc_mmio + HC_IRQ_CAUSE_OFS);
+                if (count)
+                        coal_enable |= PORTS_4_7_COAL_DONE;
         }
-        if (!count)
-                coal_enable = 0;
-        mv_set_main_irq_mask(host, coal_disable, coal_enable);
 
+        mv_set_main_irq_mask(host, 0, coal_enable);
         spin_unlock_irqrestore(&host->lock, flags);
 }