sata_svw: check DMA start bit before reset

If kdump is triggered with pending IO, controller may not respond causing
kdump to fail.

http://marc.info/?l=linux-ide&m=133032255424658&w=2

During error recovery ata_do_dev_read_id never completes due hang
in mmio_insw.

ata_do_dev_read_id
 ata_sff_data_xfer
  ioread16_rep
   mmio_insw

if DMA start bit is cleared before reset, PIO command is successful
and kdump succeeds.

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/ata/sata_svw.c b/drivers/ata/sata_svw.c
index 44a4256533e1..08608de87e4e 100644
--- a/drivers/ata/sata_svw.c
+++ b/drivers/ata/sata_svw.c
@@ -142,6 +142,39 @@ static int k2_sata_scr_write(struct ata_link *link,
         return 0;
 }
 
+static int k2_sata_softreset(struct ata_link *link,
+                             unsigned int *class, unsigned long deadline)
+{
+        u8 dmactl;
+        void __iomem *mmio = link->ap->ioaddr.bmdma_addr;
+
+        dmactl = readb(mmio + ATA_DMA_CMD);
+
+        /* Clear the start bit */
+        if (dmactl & ATA_DMA_START) {
+                dmactl &= ~ATA_DMA_START;
+                writeb(dmactl, mmio + ATA_DMA_CMD);
+        }
+
+        return ata_sff_softreset(link, class, deadline);
+}
+
+static int k2_sata_hardreset(struct ata_link *link,
+                             unsigned int *class, unsigned long deadline)
+{
+        u8 dmactl;
+        void __iomem *mmio = link->ap->ioaddr.bmdma_addr;
+
+        dmactl = readb(mmio + ATA_DMA_CMD);
+
+        /* Clear the start bit */
+        if (dmactl & ATA_DMA_START) {
+                dmactl &= ~ATA_DMA_START;
+                writeb(dmactl, mmio + ATA_DMA_CMD);
+        }
+
+        return sata_sff_hardreset(link, class, deadline);
+}
 
 static void k2_sata_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 {
@@ -346,6 +379,8 @@ static struct scsi_host_template k2_sata_sht = {
 
 static struct ata_port_operations k2_sata_ops = {
         .inherits               = &ata_bmdma_port_ops,
+        .softreset              = k2_sata_softreset,
+        .hardreset              = k2_sata_hardreset,
         .sff_tf_load            = k2_sata_tf_load,
         .sff_tf_read            = k2_sata_tf_read,
         .sff_check_status       = k2_stat_check_status,