Re: [PATCH] drivers/mci: fix read/write stalling

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Feb 27, 2012 at 11:45:28PM +0100, Robert Jarzmik wrote:
> If a read or write operation encounters an error, the card
> might stay in "recv" or "data" state, and never get back to
> "tran" state.
> 
> In these cases, the host is required to send a CMD12 (end
> transmission) to switch the FSM of the card back to "tran"
> state, as described in MMC Specification, chapter "Data
> Transfer Mode".
> 
> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
> ---
>  drivers/mci/mci-core.c |   31 ++++++++++---------------------
>  1 files changed, 10 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
> index 0bf4449..6432391 100644
> --- a/drivers/mci/mci-core.c
> +++ b/drivers/mci/mci-core.c
> @@ -101,7 +101,7 @@ static int mci_set_blocklen(struct mci *mci, unsigned len)
>  static void *sector_buf;
>  
>  /**
> - * Write one block of data to the card
> + * Write one or several blocks of data to the card
>   * @param mci_dev MCI instance
>   * @param src Where to read from to write to the card
>   * @param blocknum Block number to write
> @@ -140,23 +140,17 @@ static int mci_block_write(struct mci *mci, const void *src, int blocknum,
>  	data.flags = MMC_DATA_WRITE;
>  
>  	ret = mci_send_cmd(mci, &cmd, &data);
> -	if (ret)
> -		return ret;
> -
> -	if (blocks > 1) {
> -		mci_setup_cmd(&cmd,
> -			MMC_CMD_STOP_TRANSMISSION,
> -			0, MMC_RSP_R1b);
> -			ret = mci_send_cmd(mci, &cmd, NULL);
> -			if (ret)
> -				return ret;
> +
> +	if (ret || blocks > 1) {
> +		mci_setup_cmd(&cmd, MMC_CMD_STOP_TRANSMISSION, 0, MMC_RSP_R1b);
> +		mci_send_cmd(mci, &cmd, NULL);

Do we have to send CMD12 even when a single block transfer failed?

Sascha

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