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Commit 3780d906 authored by Wolfgang Muees's avatar Wolfgang Muees Committed by Linus Torvalds
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mmc: at91_mci: use one coherent DMA buffer 



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: default avatarWolfgang Muees <wolfgang.mues@auerswald.de>
Signed-off-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a04ac5b9

drivers/mmc/host/at91_mci.c

+24 −25
Original line number Diff line number Diff line
@@ -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 @@ static int __init at91_mci_probe(struct platform_device *pdev) 
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);