[libata] sata_sil: disable DMA engine in sil_freeze()
We must disable the DMA engine before accessing taskfile registers.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/sata_sil.c b/drivers/ata/sata_sil.c
index 35bd5cc..3cb69d5 100644
--- a/drivers/ata/sata_sil.c
+++ b/drivers/ata/sata_sil.c
@@ -565,6 +565,19 @@
tmp |= SIL_MASK_IDE0_INT << ap->port_no;
writel(tmp, mmio_base + SIL_SYSCFG);
readl(mmio_base + SIL_SYSCFG); /* flush */
+
+ /* Ensure DMA_ENABLE is off.
+ *
+ * This is because the controller will not give us access to the
+ * taskfile registers while a DMA is in progress
+ */
+ iowrite8(ioread8(ap->ioaddr.bmdma_addr) & ~SIL_DMA_ENABLE,
+ ap->ioaddr.bmdma_addr);
+
+ /* According to ata_bmdma_stop, an HDMA transition requires
+ * on PIO cycle. But we can't read a taskfile register.
+ */
+ ioread8(ap->ioaddr.bmdma_addr);
}
static void sil_thaw(struct ata_port *ap)