Subject: [PATCH] mmc: dw_mmc: fix bug that cause 'Timeout sending command'

From: [email-masked] (Jaehoon Chung)
Date: Mon, 09 Feb 2015 16:04:53 +0900

On 02/09/2015 03:56 PM, Addy wrote:
> 
> 
> On 2015.02.09 12:51, Ulf Hansson wrote:
>> On 5 February 2015 at 12:13, Addy Ke <[email-masked]> 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.

I know that it needs to check whether card is busy or not, before clock-off.
This patch seems to related with it. right?

Best Regards,
Jaehoon Chung

>>>
>>> Signed-off-by: Addy Ke <[email-masked]>
>>
>> Hi Addy,
>>
>> Should I consider $subject patch as a better option to the one below?
> No:
> This patch fix the bug, which can be found by script:
>     cd /sys/bus/platform/drivers/dwmmc_rockchip
>     for i in $(seq 1 10000); do
>       echo "========================" $i
>       echo ff0c0000.dwmmc > unbind
>       sleep .5
>       echo ff0c0000.dwmmc > bind
>       sleep 2
>     done
> 
>> [PATCH] mmc: dw_mmc: rockchip: Add DW_MCI_QUIRK_RETRY_DELAY
> This patch is for tuning issue: we should delay until card go to idle state, when the previous command return error.
>> https://lkml.org/lkml/2015/1/13/562
>>
>> Kind regards
>> Uffe
>>
>>
>>> ---
>>>   drivers/mmc/host/dw_mmc.c | 23 +++++++++++++++++++++++
>>>   1 file changed, 23 insertions(+)
>>>
>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>> index 4d2e3c2..b1d6dfb 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 +889,26 @@ 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);
>>> +
>>> +       while (time_before(jiffies, timeout)) {
>>> +               if (!dw_mci_card_busy(slot->mmc))
>>> +                       return;
>>> +       }
>>> +       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);
>>> +}
>>> +
>>>   static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
>>>   {
>>>          struct dw_mci *host = slot->host;
>>> @@ -899,6 +920,8 @@ 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);
>>> -- 
>>> 1.8.3.2
>>>
>>>
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>>
>>
> 
> 
>