On Sun, Dec 19, 2010 at 11:52 PM, Philip Rakity <prakity@xxxxxxxxxxx> wrote:
>
> 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.
>
We found some controller can not support cmd19 & cmd14 well, such as
pxa955, also mmp2 will support these two cmd after A2.
Here just send as reference in case still other controller has the same issue.
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>
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