sdhci: use PIO when DMA can't satisfy the request
Some controllers have been designed on the assumption that all transfers
will be 32-bit aligned, both in start address and in size. This is not a
guarantee the SDHCI specification provides and not one we can provide.
Revert back to PIO for individual requests in order to work around the
hardware bug.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 758a741..a5300f2 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -43,6 +43,10 @@
#define SDHCI_QUIRK_RESET_CMD_DATA_ON_IOS (1<<4)
/* Controller has an unusable DMA engine */
#define SDHCI_QUIRK_BROKEN_DMA (1<<5)
+/* Controller can only DMA from 32-bit aligned addresses */
+#define SDHCI_QUIRK_32BIT_DMA_ADDR (1<<6)
+/* Controller can only DMA chunk sizes that are a multiple of 32 bits */
+#define SDHCI_QUIRK_32BIT_DMA_SIZE (1<<7)
static const struct pci_device_id pci_ids[] __devinitdata = {
{
@@ -429,7 +433,29 @@
writeb(count, host->ioaddr + SDHCI_TIMEOUT_CONTROL);
- if (host->flags & SDHCI_USE_DMA) {
+ if (host->flags & SDHCI_USE_DMA)
+ host->flags |= SDHCI_REQ_USE_DMA;
+
+ if (unlikely((host->flags & SDHCI_REQ_USE_DMA) &&
+ (host->chip->quirks & SDHCI_QUIRK_32BIT_DMA_SIZE) &&
+ ((data->blksz * data->blocks) & 0x3))) {
+ DBG("Reverting to PIO because of transfer size (%d)\n",
+ data->blksz * data->blocks);
+ host->flags &= ~SDHCI_REQ_USE_DMA;
+ }
+
+ /*
+ * The assumption here being that alignment is the same after
+ * translation to device address space.
+ */
+ if (unlikely((host->flags & SDHCI_REQ_USE_DMA) &&
+ (host->chip->quirks & SDHCI_QUIRK_32BIT_DMA_ADDR) &&
+ (data->sg->offset & 0x3))) {
+ DBG("Reverting to PIO because of bad alignment\n");
+ host->flags &= ~SDHCI_REQ_USE_DMA;
+ }
+
+ if (host->flags & SDHCI_REQ_USE_DMA) {
int count;
count = pci_map_sg(host->chip->pdev, data->sg, data->sg_len,
@@ -466,7 +492,7 @@
mode |= SDHCI_TRNS_MULTI;
if (data->flags & MMC_DATA_READ)
mode |= SDHCI_TRNS_READ;
- if (host->flags & SDHCI_USE_DMA)
+ if (host->flags & SDHCI_REQ_USE_DMA)
mode |= SDHCI_TRNS_DMA;
writew(mode, host->ioaddr + SDHCI_TRANSFER_MODE);
@@ -482,7 +508,7 @@
data = host->data;
host->data = NULL;
- if (host->flags & SDHCI_USE_DMA) {
+ if (host->flags & SDHCI_REQ_USE_DMA) {
pci_unmap_sg(host->chip->pdev, data->sg, data->sg_len,
(data->flags & MMC_DATA_READ)?PCI_DMA_FROMDEVICE:PCI_DMA_TODEVICE);
}
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 05195ea..e4d77b0 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -171,7 +171,8 @@
spinlock_t lock; /* Mutex */
int flags; /* Host attributes */
-#define SDHCI_USE_DMA (1<<0)
+#define SDHCI_USE_DMA (1<<0) /* Host is DMA capable */
+#define SDHCI_REQ_USE_DMA (1<<1) /* Use DMA for this req. */
unsigned int max_clk; /* Max possible freq (MHz) */
unsigned int timeout_clk; /* Timeout freq (KHz) */