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mmc: at91_mci: use DMA buffer for read
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Convert the read to use the DMA buffer as well.  The old code was doing
double-buffering DMA with the PDC; no way to make it work.  Replace it
with a single-PDC approach.  It also simplify things removing the need for
a pre_dma_read() function.

[nicolas.ferre@atmel.com coding style modifications]
Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Wolfgang Muees authored and Linus Torvalds committed Mar 6, 2010
1 parent 3780d90 commit 86ee26f
Showing 1 changed file with 32 additions and 96 deletions.
128 changes: 32 additions & 96 deletions drivers/mmc/host/at91_mci.c
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Original file line number Diff line number Diff line change
Expand Up @@ -250,81 +250,15 @@ static inline void at91_mci_sg_to_dma(struct at91mci_host *host, struct mmc_data
BUG_ON(size != 0);
}

/*
* Prepare a dma read
*/
static void at91_mci_pre_dma_read(struct at91mci_host *host)
{
int i;
struct scatterlist *sg;
struct mmc_command *cmd;
struct mmc_data *data;

pr_debug("pre dma read\n");

cmd = host->cmd;
if (!cmd) {
pr_debug("no command\n");
return;
}

data = cmd->data;
if (!data) {
pr_debug("no data\n");
return;
}

for (i = 0; i < 2; i++) {
/* nothing left to transfer */
if (host->transfer_index >= data->sg_len) {
pr_debug("Nothing left to transfer (index = %d)\n", host->transfer_index);
break;
}

/* Check to see if this needs filling */
if (i == 0) {
if (at91_mci_read(host, ATMEL_PDC_RCR) != 0) {
pr_debug("Transfer active in current\n");
continue;
}
}
else {
if (at91_mci_read(host, ATMEL_PDC_RNCR) != 0) {
pr_debug("Transfer active in next\n");
continue;
}
}

/* Setup the next transfer */
pr_debug("Using transfer index %d\n", host->transfer_index);

sg = &data->sg[host->transfer_index++];
pr_debug("sg = %p\n", sg);

sg->dma_address = dma_map_page(NULL, sg_page(sg), sg->offset, sg->length, DMA_FROM_DEVICE);

pr_debug("dma address = %08X, length = %d\n", sg->dma_address, sg->length);

if (i == 0) {
at91_mci_write(host, ATMEL_PDC_RPR, sg->dma_address);
at91_mci_write(host, ATMEL_PDC_RCR, (data->blksz & 0x3) ? sg->length : sg->length / 4);
}
else {
at91_mci_write(host, ATMEL_PDC_RNPR, sg->dma_address);
at91_mci_write(host, ATMEL_PDC_RNCR, (data->blksz & 0x3) ? sg->length : sg->length / 4);
}
}

pr_debug("pre dma read done\n");
}

/*
* Handle after a dma read
*/
static void at91_mci_post_dma_read(struct at91mci_host *host)
{
struct mmc_command *cmd;
struct mmc_data *data;
unsigned int len, i, size;
unsigned *dmabuf = host->buffer;

pr_debug("post dma read\n");

Expand All @@ -340,42 +274,39 @@ static void at91_mci_post_dma_read(struct at91mci_host *host)
return;
}

while (host->in_use_index < host->transfer_index) {
struct scatterlist *sg;
size = data->blksz * data->blocks;
len = data->sg_len;

pr_debug("finishing index %d\n", host->in_use_index);
at91_mci_write(host, AT91_MCI_IDR, AT91_MCI_ENDRX);
at91_mci_write(host, AT91_MCI_IER, AT91_MCI_RXBUFF);

sg = &data->sg[host->in_use_index++];
for (i = 0; i < len; i++) {
struct scatterlist *sg;
int amount;
unsigned int *sgbuffer;

pr_debug("Unmapping page %08X\n", sg->dma_address);
sg = &data->sg[i];

dma_unmap_page(NULL, sg->dma_address, sg->length, DMA_FROM_DEVICE);
sgbuffer = kmap_atomic(sg_page(sg), KM_BIO_SRC_IRQ) + sg->offset;
amount = min(size, sg->length);
size -= amount;

if (cpu_is_at91rm9200()) { /* AT91RM9200 errata */
unsigned int *buffer;
int index;

/* Swap the contents of the buffer */
buffer = kmap_atomic(sg_page(sg), KM_BIO_SRC_IRQ) + sg->offset;
pr_debug("buffer = %p, length = %d\n", buffer, sg->length);

for (index = 0; index < (sg->length / 4); index++)
buffer[index] = swab32(buffer[index]);

kunmap_atomic(buffer, KM_BIO_SRC_IRQ);
for (index = 0; index < (amount / 4); index++)
sgbuffer[index] = swab32(*dmabuf++);
} else {
char *tmpv = (char *)dmabuf;
memcpy(sgbuffer, tmpv, amount);
tmpv += amount;
dmabuf = (unsigned *)tmpv;
}

flush_dcache_page(sg_page(sg));

data->bytes_xfered += sg->length;
}

/* Is there another transfer to trigger? */
if (host->transfer_index < data->sg_len)
at91_mci_pre_dma_read(host);
else {
at91_mci_write(host, AT91_MCI_IDR, AT91_MCI_ENDRX);
at91_mci_write(host, AT91_MCI_IER, AT91_MCI_RXBUFF);
kunmap_atomic(((void *)sgbuffer)-sg->offset, KM_BIO_SRC_IRQ);
dmac_flush_range((void *)sgbuffer, ((void *)sgbuffer) + amount);
data->bytes_xfered += amount;
if (size == 0)
break;
}

pr_debug("post dma read done\n");
Expand Down Expand Up @@ -610,7 +541,12 @@ static void at91_mci_send_command(struct at91mci_host *host, struct mmc_command
*/
host->total_length = 0;

at91_mci_pre_dma_read(host);
at91_mci_write(host, ATMEL_PDC_RPR, host->physical_address);
at91_mci_write(host, ATMEL_PDC_RCR, (data->blksz & 0x3) ?
(blocks * block_length) : (blocks * block_length) / 4);
at91_mci_write(host, ATMEL_PDC_RNPR, 0);
at91_mci_write(host, ATMEL_PDC_RNCR, 0);

ier = AT91_MCI_ENDRX /* | AT91_MCI_RXBUFF */;
}
else {
Expand Down

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