lkml.org 
[lkml]   [2010]   [Feb]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4/7] mmc: at91_mci: use DMA buffer for read
    Date
    From: Wolfgang Muees <wolfgang.mues@auerswald.de>

    This patch converts 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.

    Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
    [nicolas.ferre@atmel.com coding style modifications]
    Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
    ---
    drivers/mmc/host/at91_mci.c | 128 +++++++++++--------------------------------
    1 files changed, 32 insertions(+), 96 deletions(-)

    diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
    index fd01195..28fd565 100644
    --- a/drivers/mmc/host/at91_mci.c
    +++ b/drivers/mmc/host/at91_mci.c
    @@ -251,80 +251,14 @@ static inline void at91_mci_sg_to_dma(struct at91mci_host *host, struct mmc_data
    }

    /*
    - * 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");

    @@ -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");
    @@ -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 {
    --
    1.5.6.5


    \
     
     \ /
      Last update: 2010-02-26 18:41    [W:0.029 / U:30.348 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site