Le 07/09/2011 13:40, Nicolas Ferre :
> While using io multiple blocks operations, change the way that sg is built:
> use one sg entry for each block instead of aggregating the whole buffer
> in a single sg entry.
> Using a single sg entry for a multiple block command may lead to
> misunderstanding between the sd/mmc and the DMA controllers. In fact, the
> knowledge of the block length will allow both controllers to optimize burst
> sizes on internal bus while dealing with those data.
>
> Use a sg table to store start addresses of blocks within the data buffer.
Ping?
I add linaro-dev so maybe other people can be interested...
> Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> ---
> drivers/mmc/core/sdio_ops.c | 38 +++++++++++++++++++++++++++++---------
> 1 files changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c
> index f087d87..aea6978 100644
> --- a/drivers/mmc/core/sdio_ops.c
> +++ b/drivers/mmc/core/sdio_ops.c
> @@ -124,7 +124,7 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
> struct mmc_request mrq = {0};
> struct mmc_command cmd = {0};
> struct mmc_data data = {0};
> - struct scatterlist sg;
> + struct sg_table sgt;
>
> BUG_ON(!card);
> BUG_ON(fn > 7);
> @@ -144,24 +144,44 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
> cmd.arg |= fn << 28;
> cmd.arg |= incr_addr ? 0x04000000 : 0x00000000;
> cmd.arg |= addr << 9;
> - if (blocks == 1 && blksz <= 512)
> - cmd.arg |= (blksz == 512) ? 0 : blksz; /* byte mode */
> - else
> - cmd.arg |= 0x08000000 | blocks; /* block mode */
> + if (blocks == 1 && blksz <= 512) {
> + /* byte mode */
> + struct scatterlist sg;
> +
> + cmd.arg |= (blksz == 512) ? 0 : blksz;
> + sg_init_one(&sg, buf, blksz * blocks);
> +
> + data.sg = &sg;
> + data.sg_len = 1;
> + } else {
> + /* block mode */
> + struct scatterlist *sg_ptr;
> + int i;
> +
> + cmd.arg |= 0x08000000 | blocks;
> + if (sg_alloc_table(&sgt, blocks, GFP_KERNEL))
> + return -ENOMEM;
> + for_each_sg(sgt.sgl, sg_ptr, sgt.nents, i) {
> + sg_set_buf(sg_ptr, buf + i * blksz, blksz);
> + }
> +
> + data.sg = sgt.sgl;
> + data.sg_len = sgt.nents;
> + }
> +
> cmd.flags = MMC_RSP_SPI_R5 | MMC_RSP_R5 | MMC_CMD_ADTC;
>
> data.blksz = blksz;
> data.blocks = blocks;
> data.flags = write ? MMC_DATA_WRITE : MMC_DATA_READ;
> - data.sg = &sg;
> - data.sg_len = 1;
> -
> - sg_init_one(&sg, buf, blksz * blocks);
>
> mmc_set_data_timeout(&data, card);
>
> mmc_wait_for_req(card->host, &mrq);
>
> + if (blocks != 1 || blksz > 512)
> + sg_free_table(&sgt);
> +
> if (cmd.error)
> return cmd.error;
> if (data.error)
Best regards,
--
Nicolas Ferre
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