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mmc: at91_mci: use one coherent DMA buffer

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The TX DMA buffer is allocated only once, because the
allocation/deallocation of the buffer for EACH chunk of data is
time-consuming and prone to memory fragmentation.

Using a coherent DMA buffer avoids extra data cache calls.

[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>
This commit is contained in:
Wolfgang Muees 2010-03-05 13:43:40 -08:00 committed by Linus Torvalds
parent a04ac5b9b4
commit 3780d90602
1 changed files with 24 additions and 25 deletions
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49
drivers/mmc/host/at91_mci.c
View File

@ -88,6 +88,10 @@
#define at91_mci_read(host, reg) __raw_readl((host)->baseaddr + (reg))
#define at91_mci_write(host, reg, val) __raw_writel((val), (host)->baseaddr + (reg))
#define MCI_BLKSIZE 512
#define MCI_MAXBLKSIZE 4095
#define MCI_BLKATONCE 256
#define MCI_BUFSIZE (MCI_BLKSIZE * MCI_BLKATONCE)
/*
* Low level type for this driver
@ -604,7 +608,6 @@ static void at91_mci_send_command(struct at91mci_host *host, struct mmc_command
/*
* Handle a read
*/
host->buffer = NULL;
host->total_length = 0;
at91_mci_pre_dma_read(host);
@ -623,20 +626,8 @@ static void at91_mci_send_command(struct at91mci_host *host, struct mmc_command
if (host->total_length < 12)
host->total_length = 12;
host->buffer = kmalloc(host->total_length, GFP_KERNEL);
if (!host->buffer) {
pr_debug("Can't alloc tx buffer\n");
cmd->error = -ENOMEM;
mmc_request_done(host->mmc, host->request);
return;
}
at91_mci_sg_to_dma(host, data);
host->physical_address = dma_map_single(NULL,
host->buffer, host->total_length,
DMA_TO_DEVICE);
pr_debug("Transmitting %d bytes\n", host->total_length);
at91_mci_write(host, ATMEL_PDC_TPR, host->physical_address);
@ -703,14 +694,6 @@ static void at91_mci_completed_command(struct at91mci_host *host, unsigned int s
cmd->resp[2] = at91_mci_read(host, AT91_MCI_RSPR(2));
cmd->resp[3] = at91_mci_read(host, AT91_MCI_RSPR(3));
if (host->buffer) {
dma_unmap_single(NULL,
host->physical_address, host->total_length,
DMA_TO_DEVICE);
kfree(host->buffer);
host->buffer = NULL;
}
pr_debug("Status = %08X/%08x [%08X %08X %08X %08X]\n",
status, at91_mci_read(host, AT91_MCI_SR),
cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3]);
@ -1012,12 +995,12 @@ static int __init at91_mci_probe(struct platform_device *pdev)
mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
mmc->caps = MMC_CAP_SDIO_IRQ;
mmc->max_blk_size = 4095;
mmc->max_blk_count = mmc->max_req_size;
mmc->max_blk_size = MCI_MAXBLKSIZE;
mmc->max_blk_count = MCI_BLKATONCE;
mmc->max_req_size = MCI_BUFSIZE;
host = mmc_priv(mmc);
host->mmc = mmc;
host->buffer = NULL;
host->bus_mode = 0;
host->board = pdev->dev.platform_data;
if (host->board->wire4) {
@ -1028,6 +1011,14 @@ static int __init at91_mci_probe(struct platform_device *pdev)
" - using 1 wire\n");
}
host->buffer = dma_alloc_coherent(&pdev->dev, MCI_BUFSIZE,
&host->physical_address, GFP_KERNEL);
if (!host->buffer) {
ret = -ENOMEM;
dev_err(&pdev->dev, "Can't allocate transmit buffer\n");
goto fail5;
}
/*
* Reserve GPIOs ... board init code makes sure these pins are set
* up as GPIOs with the right direction (input, except for vcc)
@ -1036,7 +1027,7 @@ static int __init at91_mci_probe(struct platform_device *pdev)
ret = gpio_request(host->board->det_pin, "mmc_detect");
if (ret < 0) {
dev_dbg(&pdev->dev, "couldn't claim card detect pin\n");
goto fail5;
goto fail4b;
}
}
if (host->board->wp_pin) {
@ -1136,6 +1127,10 @@ fail3:
fail4:
if (host->board->det_pin)
gpio_free(host->board->det_pin);
fail4b:
if (host->buffer)
dma_free_coherent(&pdev->dev, MCI_BUFSIZE,
host->buffer, host->physical_address);
fail5:
mmc_free_host(mmc);
fail6:
@ -1158,6 +1153,10 @@ static int __exit at91_mci_remove(struct platform_device *pdev)
host = mmc_priv(mmc);
if (host->buffer)
dma_free_coherent(&pdev->dev, MCI_BUFSIZE,
host->buffer, host->physical_address);
if (host->board->det_pin) {
if (device_can_wakeup(&pdev->dev))
free_irq(gpio_to_irq(host->board->det_pin), host);