On Dec 20, 2010, at 12:24 AM, zhangfei gao wrote:
> 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.
mmp2 supports cmd19 and cmd14 today. My testing shows bit width testing
works. The time taken for the cmd19/cmd14 exchange will improve in future.
> Here just send as reference in case still other controller has the same issue.
>
>>> --
>>> 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
