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sdhci: use PIO when DMA can't satisfy the request

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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>
This commit is contained in:
Pierre Ossman 2007-12-02 19:52:11 +01:00
parent c6573c9467
commit c9fddbc4f8
2 changed files with 31 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/mmc/host/sdhci.c
View File

@ -43,6 +43,10 @@ static unsigned int debug_quirks = 0;
#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 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
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 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
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 @@ static void sdhci_finish_data(struct sdhci_host *host)
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);
}

3
drivers/mmc/host/sdhci.h
View File

@ -171,7 +171,8 @@ struct sdhci_host {
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) */