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

[Jaehoon Chung <jh80.chung@samsung.com>]

Dear, Ulf.

On 02/11/2015 12:25 PM, Ulf Hansson wrote:
> On 11 February 2015 at 03:57, Addy <addy.ke@rock-chips.com> wrote:
>>
>> On 2015/02/10 23:22, Alim Akhtar wrote:
>>>
>>> Hi Addy,
>>>
>>> On Mon, Feb 9, 2015 at 12:55 PM, Addy Ke <addy.ke@rock-chips.com> 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);
>>>> +
>>>
>>> Why 500 msec?
>>
>> This timeout value is the same as  mci_send_cmd:
>> static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
>> {
>>         struct dw_mci *host = slot->host;
>>         unsigned long timeout = jiffies + msecs_to_jiffies(500);
>>         ....
>> }
>>
>> I have not clear that which is suitable.
>> Do you have any suggestion on it?
>>>
>>>
>>>> +       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);
>>>> +
>>>
>>> Why you need to reset all blocks? may be CTRL_RESET is good enough here.
>>
>> I have tested on rk3288, if only reset ctroller, data busy bit will not be
>> cleaned,and we will still get
>>
>> "Timeout sending command".
>>
>>>
>>>> +       /* 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);
>>>>
>>> hmm...I would suggest you to call dw_mci_wait_busy() from inside
>>> mci_send_cmd(), seems like dw_mmc hangs while sending update clock cmd
>>> in multiple cases.see [1]
>>>
>>> [1]: http://permalink.gmane.org/gmane.linux.kernel.mmc/31140
>>
>> I think this patch is more reasonable.
>> So I will resend patches based on this patch.
>> thank you!
> 
> Addy, Jaehoon,
> 
> It would simply things if I could get pull requests for patches of
> dw_mmc. It's currently a bit hard to keep track and follow the
> progress all the time.
> Anyone volunteering in helping out here? :-)

If you are ok, i will do it..

Best Regards,
Jaehoon Chung

> 
> Kind regards
> Uffe
>