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

Ulf Hansson
2015-02-11T03:25:03Z

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? :-)

Kind regards
Uffe