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
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