Re: [PATCH v4 3/3] mmc: dw_mmc: Don't start command while data busy
From: Doug Anderson
Date: Thu Feb 19 2015 - 19:21:41 EST
On Fri, Feb 13, 2015 at 10:17 PM, Addy Ke <addy.ke@xxxxxxxxxxxxxx> wrote:
> We should wait until unbusy before the next request.
> But this does't need if the command is CMD13, which can access
> SD Status register regardless of data busy.
> Signed-off-by: Addy Ke <addy.ke@xxxxxxxxxxxxxx>
> Changes in v4:
> - CMD13 doesn't need wait until unbusy.
> drivers/mmc/host/dw_mmc.c | 4 ++++
> 1 file changed, 4 insertions(+)
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index ac21863..692d97a 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1076,6 +1076,10 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
> + /* Wait until unbusy if the command isn't CMD13 */
> + if (mrq->cmd->opcode != MMC_SEND_STATUS)
> + dw_mci_wait_busy(slot);
I think you need to be more general. You really should be checking
"cmd_flags & SDMMC_CMD_PRV_DAT_WAIT". That leverages dw_mmc's
knowledge about whether it needs to wait. Right now you'll be waiting
for CMD52 (SDIO) which I don't think is a good idea.
It also seems like this would be better in dw_mci_start_command() so
that we have the least chance of hitting the case. The downside is
that you can't sleep there, though... Hrm.
I updated a version of my take on this at
<https://chromium-review.googlesource.com/#/c/244850/>. I'll put a
timeout on it soon-ish. Any extra testing that folks can do would be
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