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Subject[PATCH v6 2/3]mmc: do HW reset if eMMC card occurs timeout error
Two new callbacks were added in mmc_bus_ops to implement this.
hwreset_emmc: trigger a RST_n signal for host to reset card.
reinit_emmc: reinitialize eMMC card after hardware reset occurs.

MMC core layer will check whether occurs a timeout error in the new added
function mmc_handle_timeout_error.

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
---
drivers/mmc/card/block.c | 10 +++++++++
drivers/mmc/core/core.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/mmc/core/core.h | 26 ++++++++++++++++++++++++
include/linux/mmc/core.h | 1 +
4 files changed, 85 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 217f820..ba9614d 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -424,6 +424,16 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)

mmc_wait_for_req(card->host, &brq.mrq);

+ /* Check if need to do HW reset */
+ if (brq.cmd.error)
+ mmc_handle_timeout_error(card->host, brq.cmd.error);
+
+ if (brq.data.error)
+ mmc_handle_timeout_error(card->host, brq.data.error);
+
+ if (brq.stop.error)
+ mmc_handle_timeout_error(card->host, brq.stop.error);
+
mmc_queue_bounce_post(mq);

/*
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index a8e89f3..795bd81 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -83,6 +83,52 @@ static void mmc_flush_scheduled_work(void)
}

/**
+ * mmc_handle_timeout_error - handle timeout errors occurs by card
+ * @host: MMC host used to handle error
+ * @error: error condition
+ *
+ * check whether there is a command or data timeout error occurred,
+ * if so, reset and reinit eMMC card if card has such capability.
+ *
+ * In this function, driver will do follow things:
+ * 1. let host controller do a specific hardware reset for eMMC
+ * card (trigger RST_n signal).
+ * 2. after reset done, reinit eMMC card.
+ */
+void mmc_handle_timeout_error(struct mmc_host *host, int error)
+{
+ struct mmc_card *card = host->card;
+
+ /*
+ * If error condition is not timeout, do nothing
+ */
+ if (error != -ETIMEDOUT)
+ return;
+ /*
+ * make sure card is not NULL
+ * make sure mmc_card has HW reset capability
+ */
+ if (!card || !card->ext_csd.rst)
+ return;
+
+ /* check whether host has such callback */
+ if (!host->bus_ops->hwreset_emmc ||
+ !host->bus_ops->reinit_emmc)
+ return;
+
+ /*
+ * if there occurs any timeout error, HW reset
+ * eMMC card and reinit again.
+ */
+ if (host->bus_ops->hwreset_emmc(host))
+ pr_warn("MMC card reset failed\n");
+ else
+ if (host->bus_ops->reinit_emmc(host))
+ pr_warn("MMC card reinit failed\n");
+}
+EXPORT_SYMBOL(mmc_handle_timeout_error);
+
+/**
* mmc_request_done - finish processing an MMC request
* @host: MMC host which completed request
* @mrq: MMC request which request
@@ -1341,6 +1387,8 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
if (err) {
printk(KERN_ERR "mmc_erase: erase error %d, status %#x\n",
err, cmd.resp[0]);
+ /* Before return, check whether can do a HW reset */
+ mmc_handle_timeout_error(card->host, cmd.error);
err = -EIO;
goto out;
}
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 026c975..09b6c54 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -24,6 +24,32 @@ struct mmc_bus_ops {
int (*resume)(struct mmc_host *);
int (*power_save)(struct mmc_host *);
int (*power_restore)(struct mmc_host *);
+ /*
+ * New added callback
+ * This function is used to reinitialize eMMC card after eMMC card been
+ * reset.
+ *
+ * Note 1: before calling this, mmc_claim_host is needed. After finish
+ * this calling, mmc_release_host is needed.
+ *
+ * return value:
+ * 0 - successfully reinit card
+ * other - failed to reinit
+ */
+ int (*reinit_emmc)(struct mmc_host *);
+ /*
+ * New added callback
+ * This function is used to trigger RST_n signal to reset eMMC card as
+ * eMMC4.4 spec recommended.
+ *
+ * Note 1: this function may sleep since delay is needed when pull
+ * up/down GPIO line.
+ *
+ * return value:
+ * 0 - successfully reset eMMC card
+ * other - failed to reset eMMC card
+ */
+ int (*hwreset_emmc)(struct mmc_host *);
};

void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 64e013f..115d589 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -131,6 +131,7 @@ struct mmc_request {
struct mmc_host;
struct mmc_card;

+extern void mmc_handle_timeout_error(struct mmc_host *, int);
extern void mmc_wait_for_req(struct mmc_host *, struct mmc_request *);
extern int mmc_wait_for_cmd(struct mmc_host *, struct mmc_command *, int);
extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
--
1.6.6.1


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