Re: [PATCH v2 1/2] mmc: dw_mmc: fix bug that cause 'Timeout sending command'

[Addy]

On 2015/02/09 18:01, Jaehoon Chung wrote:
> Hi, Addy.
>
> On 02/09/2015 04:25 PM, Addy Ke wrote:
> > Because of some uncertain factors, such as worse card or worse hardware,
> > DAT[3:0](the data lines) may be pulled down by card, and mmc controller
> > will be in busy state. This should not happend when mmc controller
> > send command to update card clocks. If this happends, mci_send_cmd will
> > be failed and we will get 'Timeout sending command', and then system will
> > be blocked. To avoid this, we need reset mmc controller.
> >
> > Signed-off-by: Addy Ke <addy.ke@xxxxxxxxxxxxxx>
> > ---
> >   drivers/mmc/host/dw_mmc.c | 28 ++++++++++++++++++++++++++++
> >   1 file changed, 28 insertions(+)
> >
> > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> > index 4d2e3c2..b0b57e3 100644
> > --- a/drivers/mmc/host/dw_mmc.c
> > +++ b/drivers/mmc/host/dw_mmc.c
> > @@ -100,6 +100,7 @@ struct idmac_desc {
> >   };
> >   #endif /* CONFIG_MMC_DW_IDMAC */
> >   
> > +static int dw_mci_card_busy(struct mmc_host *mmc);
> >   static bool dw_mci_reset(struct dw_mci *host);
> >   static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset);
> >   
> > @@ -888,6 +889,31 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
> >   		cmd, arg, cmd_status);
> >   }
> >   
> > +static void dw_mci_wait_busy(struct dw_mci_slot *slot)
> > +{
> > +	struct dw_mci *host = slot->host;
> > +	unsigned long timeout = jiffies + msecs_to_jiffies(500);
> > +
> > +	do {
> > +		if (!dw_mci_card_busy(slot->mmc))
> > +			return;
> > +		cpu_relax();
> > +	} while (time_before(jiffies, timeout));
> > +
> > +	dev_err(host->dev, "Data busy (status %#x)\n",
> > +		mci_readl(slot->host, STATUS));
> > +
> > +	/*
> > +	 * Data busy, this should not happend when mmc controller send command
> > +	 * to update card clocks in non-volt-switch state. If it happends, we
> > +	 * should reset controller to avoid getting "Timeout sending command".
> > +	 */
> > +	dw_mci_ctrl_reset(host, SDMMC_CTRL_ALL_RESET_FLAGS);
> If reset is failed, then dw_mci_ctrl_reset should return "false".
>
> 	ret = dw_mci_ctrl_reset();
>
> 	WARN_ON(!ret || dw_mci_card_busy(slot->mmc));
>
> Is it right?
you are right, and I will update it in my next version patch. thank you.
> In my experiment, if reset is failed or card is busy, eMMC can't work anymore..right?
> I think this patch is reasonable to prevent blocking issue.
>
> Best Regards,
> Jaehoon Chung
>
>
> > +
> > +	/* Fail to reset controller or still data busy, WARN_ON! */
> > +	WARN_ON(dw_mci_card_busy(slot->mmc));
> > +}
> > +
> >   static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
> >   {
> >   	struct dw_mci *host = slot->host;
> > @@ -899,6 +925,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
> >   	/* We must continue to set bit 28 in CMD until the change is complete */
> >   	if (host->state == STATE_WAITING_CMD11_DONE)
> >   		sdmmc_cmd_bits |= SDMMC_CMD_VOLT_SWITCH;
> > +	else
> > +		dw_mci_wait_busy(slot);
> >   
> >   	if (!clock) {
> >   		mci_writel(host, CLKENA, 0);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/