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

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@rock-chips.com>
>> ---
>> 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);
>>
>
>
>




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