Re: [PATCH v4 3/3] mmc: dw_mmc: Don't start command while data busy

[Doug Anderson]

Addy,

On Fri, Feb 13, 2015 at 10:17 PM, Addy Ke  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 
> ---
> 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)
>
> WARN_ON(slot->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
.  I'll put a
timeout on it soon-ish.  Any extra testing that folks can do would be
appreciated...

-Doug
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[PATCH v4 3/3] mmc: dw_mmc: Don't start command while data busy

[Addy Ke]

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 
---
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)
 
WARN_ON(slot->mrq);
 
+   /* Wait until unbusy if the command isn't CMD13 */
+   if (mrq->cmd->opcode != MMC_SEND_STATUS)
+   dw_mci_wait_busy(slot);
+
/*
 * The check for card presence and queueing of the request must be
 * atomic, otherwise the card could be removed in between and the
-- 
1.8.3.2


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