[PATCH] sata_sil24: implement loss of completion interrupt on PCI-X errta fix

SiI3124 might lose completion interrupt if completion interrupt occurs
shortly after SLOT_STAT register is read for the previous completion
interrupt if it is operating in PCI-X mode.

This currently doesn't trigger as libata never queues more than one
command, but it will with NCQ changes.  This patch implements the
workaround - turning on WoC and explicitly clearing interrupt.

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

1 files changed, 25 insertions, 2 deletions

diff --git a/drivers/scsi/sata_sil24.c b/drivers/scsi/sata_sil24.c
index 50c2c6bcba6e..c535607e995a 100644
--- a/drivers/scsi/sata_sil24.c
+++ b/drivers/scsi/sata_sil24.c
@@ -221,6 +221,7 @@ enum {
         /* host flags */
         SIL24_COMMON_FLAGS      = ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY |
                                   ATA_FLAG_MMIO | ATA_FLAG_PIO_DMA,
+        SIL24_FLAG_PCIX_IRQ_WOC = (1 << 24), /* IRQ loss errata on PCI-X */
 
         IRQ_STAT_4PORTS         = 0xf,
 };
@@ -348,7 +349,8 @@ static struct ata_port_info sil24_port_info[] = {
         /* sil_3124 */
         {
                 .sht            = &sil24_sht,
-                .host_flags     = SIL24_COMMON_FLAGS | SIL24_NPORTS2FLAG(4),
+                .host_flags     = SIL24_COMMON_FLAGS | SIL24_NPORTS2FLAG(4) |
+                                  SIL24_FLAG_PCIX_IRQ_WOC,
                 .pio_mask       = 0x1f,                 /* pio0-4 */
                 .mwdma_mask     = 0x07,                 /* mwdma0-2 */
                 .udma_mask      = 0x3f,                 /* udma0-5 */
@@ -737,6 +739,10 @@ static inline void sil24_host_intr(struct ata_port *ap)
         slot_stat = readl(port + PORT_SLOT_STAT);
         if (!(slot_stat & HOST_SSTAT_ATTN)) {
                 struct sil24_port_priv *pp = ap->private_data;
+
+                if (ap->flags & SIL24_FLAG_PCIX_IRQ_WOC)
+                        writel(PORT_IRQ_COMPLETE, port + PORT_IRQ_STAT);
+
                 /*
                  * !HOST_SSAT_ATTN guarantees successful completion,
                  * so reading back tf registers is unnecessary for
@@ -868,6 +874,7 @@ static int sil24_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         void __iomem *host_base = NULL;
         void __iomem *port_base = NULL;
         int i, rc;
+        u32 tmp;
 
         if (!printed_version++)
                 dev_printk(KERN_DEBUG, &pdev->dev, "version " DRV_VERSION "\n");
@@ -941,13 +948,23 @@ static int sil24_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         /* GPIO off */
         writel(0, host_base + HOST_FLASH_CMD);
 
+        /* Apply workaround for completion IRQ loss on PCI-X errata */
+        if (probe_ent->host_flags & SIL24_FLAG_PCIX_IRQ_WOC) {
+                tmp = readl(host_base + HOST_CTRL);
+                if (tmp & (HOST_CTRL_TRDY | HOST_CTRL_STOP | HOST_CTRL_DEVSEL))
+                        dev_printk(KERN_INFO, &pdev->dev,
+                                   "Applying completion IRQ loss on PCI-X "
+                                   "errata fix\n");
+                else
+                        probe_ent->host_flags &= ~SIL24_FLAG_PCIX_IRQ_WOC;
+        }
+
         /* clear global reset & mask interrupts during initialization */
         writel(0, host_base + HOST_CTRL);
 
         for (i = 0; i < probe_ent->n_ports; i++) {
                 void __iomem *port = port_base + i * PORT_REGS_SIZE;
                 unsigned long portu = (unsigned long)port;
-                u32 tmp;
 
                 probe_ent->port[i].cmd_addr = portu + PORT_PRB;
                 probe_ent->port[i].scr_addr = portu + PORT_SCONTROL;
@@ -969,6 +986,12 @@ static int sil24_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
                                            "failed to clear port RST\n");
                 }
 
+                /* Configure IRQ WoC */
+                if (probe_ent->host_flags & SIL24_FLAG_PCIX_IRQ_WOC)
+                        writel(PORT_CS_IRQ_WOC, port + PORT_CTRL_STAT);
+                else
+                        writel(PORT_CS_IRQ_WOC, port + PORT_CTRL_CLR);
+
                 /* Zero error counters. */
                 writel(0x8000, port + PORT_DECODE_ERR_THRESH);
                 writel(0x8000, port + PORT_CRC_ERR_THRESH);