Re: [PATCH] OMAP: MMC: recover from transfer failures

Adrian Hunter
2009-01-08T08:51:54Z

Jean Pihet wrote:
> Tony, Pierre,
>
> Here is a patch that fixes a MMC host controller deadlock. The problem happens
> when removing the MMC/SD device when a transfer is on-going.
>
> It has been tested on OMAP3430 but this fix should apply to OMAP2 chips as
> well, as seen from the TRMs.
>
> What do you think?
>
> Regards,
> Jean.
>
> OMAP: MMC: recover from transfer failures
>
> Timeouts during a command that has a data phase can result in the
> next command issued after the command that failed not being processed,
> i.e. no interrupt ever occurs to indicate the command has completed.
> This failure can result in a deadlock.
>
> The indication that the mmc host controller is in this error state is
> that the DATI bit is set in the PSTATE register. This patch checks
> to see if the DATI bit is set before starting a new command, and if it
> is set it resets the data state machine to clear the error.
>
> Tested on OMAP3430 chip and intensive MMC/SD device removal while
> transferring data.
>
> Regards,
> Jean
>
>
> From 48a40925a4d57f6e7e45809a4b5c09b20f9314d7 Mon Sep 17 00:00:00 2001
> From: Jean Pihet <jpihet@mvista.com>
> Date: Tue, 16 Dec 2008 19:44:12 +0100
> Subject: [PATCH] OMAP: MMC: recover from transfer failures
>
> Timeouts during a command that has a data phase can result in the
> next command issued after the command that failed not being processed,
> i.e. no interrupt ever occurs to indicate the command has completed.
> This failure can result in a deadlock.
>
> The indication that the mmc host controller is in this error state is
> that the DATI bit is set in the PSTATE register. This patch checks
> to see if the DATI bit is set before starting a new command, and if it
> is set it resets the data state machine to clear the error.
>
> Tested on OMAP3430 chip and intensive MMC/SD device removal while
> transferring data.
>
> Signed-off-by: Andy Lowe <alowe@mvista.com>
> Signed-off-by: Jean Pihet <jpihet@mvista.com>
> ---
> drivers/mmc/host/omap_hsmmc.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index 1fcc544..b7d111e 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -44,6 +44,7 @@
> #define OMAP_HSMMC_RSP54 0x0118
> #define OMAP_HSMMC_RSP76 0x011C
> #define OMAP_HSMMC_DATA 0x0120
> +#define OMAP_HSMMC_PSTATE 0x0124
> #define OMAP_HSMMC_HCTL 0x0128
> #define OMAP_HSMMC_SYSCTL 0x012C
> #define OMAP_HSMMC_STAT 0x0130
> @@ -89,6 +90,7 @@
> #define DUAL_VOLT_OCR_BIT 7
> #define SRC (1 << 25)
> #define SRD (1 << 26)
> +#define DATI (1 << 1)
>
> /*
> * FIXME: Most likely all the data using these _DEVID defines should come
> @@ -273,6 +275,15 @@ mmc_omap_start_command(struct mmc_omap_host *host, struct
> mmc_command *cmd,
> mmc_hostname(host->mmc), cmd->opcode, cmd->arg);
> host->cmd = cmd;
>
> + if (OMAP_HSMMC_READ(host->base, PSTATE) & DATI) {
> + dev_dbg(mmc_dev(host->mmc), "mmc_omap_start_command: "
> + " resetting data state machine\n");
> + OMAP_HSMMC_WRITE(host->base, SYSCTL,
> + OMAP_HSMMC_READ(host->base, SYSCTL) | SRD);
> + while (OMAP_HSMMC_READ(host->base, SYSCTL) & SRD)
> + ;
> + }
> +
> /*
> * Clear status bits and enable interrupts
> */
>

Why not do the reset in mmc_omap_irq() like the other resets?
e.g.

static irqreturn_t mmc_omap_irq(int irq, void *dev_id)
{
struct mmc_omap_host *host = dev_id;
struct mmc_data *data;
int end_cmd = 0, end_trans = 0, status;

if (host->cmd == NULL && host->data == NULL) {
OMAP_HSMMC_WRITE(host->base, STAT,
OMAP_HSMMC_READ(host->base, STAT));
return IRQ_HANDLED;
}

data = host->data;
status = OMAP_HSMMC_READ(host->base, STAT);
dev_dbg(mmc_dev(host->mmc), "IRQ Status is %x\n", status);

if (status & ERR) {
#ifdef CONFIG_MMC_DEBUG
mmc_omap_report_irq(host, status);
#endif
if ((status & CMD_TIMEOUT) ||
(status & CMD_CRC)) {
if (host->cmd) {
if (status & CMD_TIMEOUT) {
OMAP_HSMMC_WRITE(host->base, SYSCTL,
OMAP_HSMMC_READ(host->base,
SYSCTL) | SRC);
while (OMAP_HSMMC_READ(host->base,
SYSCTL) & SRC)
;

host->cmd->error = -ETIMEDOUT;
} else {
host->cmd->error = -EILSEQ;
}
end_cmd = 1;
}
- if (host->data)
+ if (host->data) {
mmc_dma_cleanup(host);
+ OMAP_HSMMC_WRITE(host->base, SYSCTL,
+ OMAP_HSMMC_READ(host->base,
+ SYSCTL) | SRD);
+ while (OMAP_HSMMC_READ(host->base,
+ SYSCTL) & SRD)
+ ;
+ }
}
if ((status & DATA_TIMEOUT) ||
(status & DATA_CRC)) {
if (host->data) {
if (status & DATA_TIMEOUT)
mmc_dma_cleanup(host);
else
host->data->error = -EILSEQ;
OMAP_HSMMC_WRITE(host->base, SYSCTL,
OMAP_HSMMC_READ(host->base,
SYSCTL) | SRD);
while (OMAP_HSMMC_READ(host->base,
SYSCTL) & SRD)
;
end_trans = 1;
}
}