On 13 April 2016 at 07:59, Yuan, Juntao <juntao.yuan@xxxxxxxxx> wrote:
>
> According to Physical Layer Simplified Specification Version 4.10, SD
> card needs a R1b response for stop command.
I have looked at this earlier and I don't think R1B is needed.
According to the Command table in the spec, where commands are listed
with their corresponding response type, a CMD12 (stop) has an R1B
response. As you probably know, the difference between R1 and R1B is
the optional busy signalling on DAT0.
Now, if you look into the details about READ and WRITE transfers in
the spec, it becomes clear that there's a difference in the response
you get from a CMD12. In the READ case there's *no* busy signalling
but there is for WRITE. For that reason, using R1 in case of READ
seems like the correct thing to do.
I haven't looked at SD 4.10, but according to earlier versions you can
find these details in the "Timings" section.
I guess some comment in the code would be valuable as the spec is
indeed a bit unclear, let me submit a change for it.
Kind regards
Uffe
>
> Signed-off-by: Yuan Juntao <juntao.yuan@xxxxxxxxx>
> ---
> drivers/mmc/card/block.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 3bdbe50..aa8fc98b 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -1533,9 +1533,14 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
> if (rq_data_dir(req) == READ) {
> brq->cmd.opcode = readcmd;
> brq->data.flags = MMC_DATA_READ;
> - if (brq->mrq.stop)
> - brq->stop.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 |
> - MMC_CMD_AC;
> + if (brq->mrq.stop) {
> + if (mmc_card_mmc(card))
> + brq->stop.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 |
> + MMC_CMD_AC;
> + else
> + brq->stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B |
> + MMC_CMD_AC;
> + }
> } else {
> brq->cmd.opcode = writecmd;
> brq->data.flags = MMC_DATA_WRITE;
> --
> 1.7.9.5
>
>
>
> Thanks.
> Juntao.
>
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