On Tue, Oct 30, 2012 at 04:54:07PM +0100, Javier Martin wrote:
> When a SD card is initialized some data transfers of 64 and 8 bytes
> are issued. It seems the DMA has some problems dealing with these kind
> of "short" transfers, leading sometimes to the SD card not being detected.
>
> In order to solve this problem, do not use DMA for transfer sizes lower
> than the sector size.
>
> Signed-off-by: Javier Martin <javier.martin@xxxxxxxxxxxxxxxxx>
Acked-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Sascha
> ---
> Changes since v1:
> - Do not remove the check "sg->length & 3".
>
> ---
> drivers/mmc/host/mxcmmc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c
> index fc42a2e..a09637f 100644
> --- a/drivers/mmc/host/mxcmmc.c
> +++ b/drivers/mmc/host/mxcmmc.c
> @@ -240,7 +240,7 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
> return 0;
>
> for_each_sg(data->sg, sg, data->sg_len, i) {
> - if (sg->offset & 3 || sg->length & 3) {
> + if (sg->offset & 3 || sg->length & 3 || sg->length < 512) {
> host->do_dma = 0;
> return 0;
> }
> --
> 1.7.9.5
>
>
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