Any comments?
Sonic
On Mon, Jul 12, 2010 at 3:50 PM, sonic zhang <sonic.adi@xxxxxxxxx> wrote:
> >From 94d1ea57ac2fbe37133e25e99ccb265250f0027d Mon Sep 17 00:00:00 2001
> From: Sonic Zhang <sonic.zhang@xxxxxxxxxx>
> Date: Fri, 9 Jul 2010 15:36:20 +0800
> Subject: [PATCH v2] MMC:mmc_spi: Recover from crc error for SD read/write operation over SPI.
>
> SPI bus is not reliable on all platforms when doing large data transfer.
> Current mmc spi driver fails SD read/write command immediately, if
> occasional CRC error is reported by SD device. This patch makes the
> operation recover from the CRC error by doing last SD command again.
> The retry count is set to 5 to ensure the driver pass any stress test.
>
> Signed-off-by: Sonic Zhang <sonic.zhang@xxxxxxxxxx>
> ---
> drivers/mmc/host/mmc_spi.c | 22 ++++++++++++++++++++++
> 1 files changed, 22 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
> index ad847a2..8192434 100644
> --- a/drivers/mmc/host/mmc_spi.c
> +++ b/drivers/mmc/host/mmc_spi.c
> @@ -1055,6 +1055,8 @@ static void mmc_spi_request(struct mmc_host *mmc, struct mmc_request *mrq)
> {
> struct mmc_spi_host *host = mmc_priv(mmc);
> int status = -EINVAL;
> + int crc_retry = 5;
> + struct mmc_command stop;
>
> #ifdef DEBUG
> /* MMC core and layered drivers *MUST* issue SPI-aware commands */
> @@ -1084,10 +1086,30 @@ static void mmc_spi_request(struct mmc_host *mmc, struct mmc_request *mrq)
> }
> #endif
>
> +crc_recover:
> /* issue command; then optionally data and stop */
> status = mmc_spi_command_send(host, mrq, mrq->cmd, mrq->data != NULL);
> if (status == 0 && mrq->data) {
> mmc_spi_data_do(host, mrq->cmd, mrq->data, mrq->data->blksz);
> +
> + /*
> + * SPI bus is not reliable when doing large data transfer.
> + * If occasional crc error is reported by SD device when do
> + * data read/write over SPI, it can be recovered by doing
> + * last SD command again. The retry count is set to 5 to
> + * ensure the driver pass any stress test.
> + */
> + if (mrq->data->error == -EILSEQ && crc_retry) {
> + stop.opcode = MMC_STOP_TRANSMISSION;
> + stop.arg = 0;
> + stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
> +
> + status = mmc_spi_command_send(host, mrq, &stop, 0);
> + crc_retry--;
> + mrq->data->error = 0;
> + goto crc_recover;
> + }
> +
> if (mrq->stop)
> status = mmc_spi_command_send(host, mrq, mrq->stop, 0);
> else
> --
> 1.6.0
>
>
>
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