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 <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
