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Subject[PATCH 3/7] mmc: at91_mci: avoid timeouts
From: Marc Pignat <marc.pignat@hevs.ch>

The at91 mci controller internal state machine seems to often crash.
This can
be fixed by resetting the controller after each command for at91rm9200
and by
setting the MCI_BLKR register on at91sam926*.

Signed-off-by: Marc Pignat <marc.pignat@hevs.ch>
Signed-off-by: Hans J Koch <hjk@linutronix.de>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
---
drivers/mmc/host/at91_mci.c | 48
++++++++++++++++++++++++++++++++++
include/asm-arm/arch-at91/at91_mci.h | 4 +++
2 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
index 4b4518f..6b9662e 100644
--- a/drivers/mmc/host/at91_mci.c
+++ b/drivers/mmc/host/at91_mci.c
@@ -130,6 +130,43 @@ struct at91mci_host
struct timer_list timer;
};

+/*
+ * Reset the controller and restore most of the state
+ */
+static void at91_reset_host(struct at91mci_host *host)
+{
+ unsigned long flags;
+ u32 mr;
+ u32 sdcr;
+ u32 dtor;
+ u32 imr;
+
+ local_irq_save(flags);
+ imr = at91_mci_read(host, AT91_MCI_IMR);
+
+ at91_mci_write(host, AT91_MCI_IDR, 0xffffffff);
+
+ /* save current state */
+ mr = at91_mci_read(host, AT91_MCI_MR) & 0x7fff;
+ sdcr = at91_mci_read(host, AT91_MCI_SDCR);
+ dtor = at91_mci_read(host, AT91_MCI_DTOR);
+
+ /* reset the controller */
+ at91_mci_write(host, AT91_MCI_CR, AT91_MCI_MCIDIS | AT91_MCI_SWRST);
+
+ /* restore state */
+ at91_mci_write(host, AT91_MCI_CR, AT91_MCI_MCIEN);
+ at91_mci_write(host, AT91_MCI_MR, mr);
+ at91_mci_write(host, AT91_MCI_SDCR, sdcr);
+ at91_mci_write(host, AT91_MCI_DTOR, dtor);
+ at91_mci_write(host, AT91_MCI_IER, imr);
+
+ /* make sure sdio interrupts will fire */
+ at91_mci_read(host, AT91_MCI_SR);
+
+ local_irq_restore(flags);
+}
+
static void at91_timeout_timer(unsigned long data)
{
struct at91mci_host *host;
@@ -148,6 +185,7 @@ static void at91_timeout_timer(unsigned long data)
host->request->cmd->error = -ETIMEDOUT;
}

+ at91_reset_host(host);
mmc_request_done(host->mmc, host->request);
}
}
@@ -512,6 +550,11 @@ static void at91_mci_send_command(struct
at91mci_host *host, struct mmc_command
mr |= AT91_MCI_PDCMODE;
at91_mci_write(host, AT91_MCI_MR, mr);

+ if (!cpu_is_at91rm9200())
+ at91_mci_write(host, AT91_MCI_BLKR,
+ AT91_MCI_BLKR_BCNT(blocks) |
+ AT91_MCI_BLKR_BLKLEN(block_length));
+
/*
* Disable the PDC controller
*/
@@ -584,6 +627,11 @@ static void at91_mci_process_next(struct
at91mci_host *host)
at91_mci_send_command(host, host->request->stop);
} else {
del_timer(&host->timer);
+ /* the at91rm9200 mci controller hangs after some transfers,
+ * and the workaround is to reset it after each transfer.
+ */
+ if (cpu_is_at91rm9200())
+ at91_reset_host(host);
mmc_request_done(host->mmc, host->request);
}
}
diff --git a/include/asm-arm/arch-at91/at91_mci.h
b/include/asm-arm/arch-at91/at91_mci.h
index 1551fc2..400ec10 100644
--- a/include/asm-arm/arch-at91/at91_mci.h
+++ b/include/asm-arm/arch-at91/at91_mci.h
@@ -75,6 +75,10 @@
#define AT91_MCI_TRTYP_MULTIPLE (1 << 19)
#define AT91_MCI_TRTYP_STREAM (2 << 19)

+#define AT91_MCI_BLKR 0x18 /* Block Register */
+#define AT91_MCI_BLKR_BCNT(n) ((0xffff & (n)) << 0) /* Block count */
+#define AT91_MCI_BLKR_BLKLEN(n) ((0xffff & (n)) << 16) /* Block lenght */
+
#define AT91_MCI_RSPR(n) (0x20 + ((n) * 4)) /* Response Registers 0-3 */
#define AT91_MCR_RDR 0x30 /* Receive Data Register */
#define AT91_MCR_TDR 0x34 /* Transmit Data Register */
--
1.5.3.7




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