Hi, Kuninori.
Subject has the typo. lultiple -> multiple?
I didn't know why you need this patch. Would you use the MMC_CAP2_NO_MULTI_READ?
And I think...it's not good that used the card's capability flags to fix your H/W bug.
Best Regards,
Jaehoon Chung
On 05/30/2014 07:40 PM, Kuninori Morimoto wrote:
> From: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
>
> In some controllers, when performing a multiple block read of
> one or two blocks, depending on the timing with which the
> response register is read, the response value may not
> be read properly.
> Use single block read for this HW bug
>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> ---
> drivers/mmc/card/block.c | 19 +++++++++++++++++--
> include/linux/mmc/host.h | 3 +++
> 2 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 452782b..f3cbe37 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -1400,8 +1400,23 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>
> /* Some controllers can't do multiblock reads due to hw bugs */
> if (card->host->caps2 & MMC_CAP2_NO_MULTI_READ &&
> - rq_data_dir(req) == READ)
> - brq->data.blocks = 1;
> + rq_data_dir(req) == READ) {
> +
> + if (card->host->caps2 & MMC_CAP2_2BLKS_LIMIT) {
> + /*
> + * In some controllers, when performing a
> + * multiple block read of one or two blocks,
> + * depending on the timing with which the
> + * response register is read, the response
> + * value may not be read properly.
> + * Use single block read for this HW bug
> + */
> + if (brq->data.blocks == 2)
> + brq->data.blocks = 1;
> + } else {
> + brq->data.blocks = 1;
> + }
> + }
> }
>
> if (brq->data.blocks > 1 || do_rel_wr) {
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index cb61ea4..5429cd7 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -266,6 +266,9 @@ struct mmc_host {
> #define MMC_CAP2_BOOTPART_NOACC (1 << 0) /* Boot partition no access */
> #define MMC_CAP2_FULL_PWR_CYCLE (1 << 2) /* Can do full power cycle */
> #define MMC_CAP2_NO_MULTI_READ (1 << 3) /* Multiblock reads don't work */
> +#define MMC_CAP2_2BLKS_LIMIT (1 << 4) /* 2 blocks limit for multi read */
> +#define MMC_CAP2_NO_2BLKS_READ (MMC_CAP2_NO_MULTI_READ | \
> + MMC_CAP2_2BLKS_LIMIT)
> #define MMC_CAP2_HS200_1_8V_SDR (1 << 5) /* can support */
> #define MMC_CAP2_HS200_1_2V_SDR (1 << 6) /* can support */
> #define MMC_CAP2_HS200 (MMC_CAP2_HS200_1_8V_SDR | \
>
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