On Dec 16, 2010, at 7:21 PM, zhangfei gao wrote:
> If controller does not support cmd19 & cmd14, here is workaround we using.
> Send just in case somebody require.
>
> From b95c5e8d1c5b42a149a521c4992dfd8fc8d61143 Mon Sep 17 00:00:00 2001
> From: Zhangfei Gao <zhangfei.gao@xxxxxxxxxxx>
> Date: Thu, 16 Dec 2010 22:28:40 -0500
> Subject: [PATCH] mmc: workaround of 1-bit mmc card
>
> In case controller does not support cmd19 & cmd14.
> Use workaround to decrease bus width when error happen via reading
> partition table
>
> Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxxx>
> ---
> drivers/mmc/card/block.c | 28 ++++++++++++++++++++++++++++
> include/linux/mmc/host.h | 2 ++
> 2 files changed, 30 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 217f820..c0d2b73 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -432,6 +432,34 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
> *mq, struct request *req)
> * programming mode even when things go wrong.
> */
> if (brq.cmd.error || brq.data.error || brq.stop.error) {
> + if (mmc_card_mmc(card)) {
> + u8 width = card->host->ios.bus_width;
> +
> + if (width == MMC_BUS_WIDTH_4) {
> + printk(KERN_WARNING "%s: "
> + "retrying using 1 BIT WIDTH \n",
> + req->rq_disk->disk_name);
> + mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> + EXT_CSD_BUS_WIDTH,
> + EXT_CSD_BUS_WIDTH_1);
> +
> + mmc_set_bus_width(card->host,
> + MMC_BUS_WIDTH_1);
> + continue;
> + }
> + if (width == MMC_BUS_WIDTH_8) {
> + printk(KERN_WARNING "%s: "
> + "retrying using 4 BIT WIDTH \n",
> + req->rq_disk->disk_name);
> + mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> + EXT_CSD_BUS_WIDTH,
> + EXT_CSD_BUS_WIDTH_4);
> +
> + mmc_set_bus_width(card->host,
> + MMC_BUS_WIDTH_4);
> + continue;
> + }
> + }
> if (brq.data.blocks > 1 && rq_data_dir(req) == READ) {
> /* Redo read one sector at a time */
> printk(KERN_WARNING "%s: retrying using single "
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 4a9d9d2..2a2c1ab 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -249,6 +249,8 @@ extern struct mmc_host *mmc_alloc_host(int extra,
> struct device *);
> extern int mmc_add_host(struct mmc_host *);
> extern void mmc_remove_host(struct mmc_host *);
> extern void mmc_free_host(struct mmc_host *);
> +extern int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value);
> +extern void mmc_set_bus_width(struct mmc_host *host, unsigned int width);
>
> static inline void *mmc_priv(struct mmc_host *host)
> {
> --
> 1.7.0.4
Curious,
What cards fail without this patch ? and on what system ?
PXA168/PXA910 and MMP2 all support bus width testing for mmc cards.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
