Re: [PATCH] mmc: dw_mmc: change to use recommended reset procedure

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, May 9, 2014 at 12:32 AM, Jaehoon Chung <jh80.chung@xxxxxxxxxxx> wrote:
> Hi, Sonny.
>
> You can discard the my previous some comment.
> As you mentioned, this reset sequence is recommended at Synopsys TRM.
>
> Add the minor question.
>
> On 05/09/2014 01:27 PM, Jaehoon Chung wrote:
>> Hi, Sonny.
>>
>> I have checked the Synopsys TRM..
>>
>> On 05/09/2014 10:34 AM, Sonny Rao wrote:
>>> On Thu, May 8, 2014 at 6:15 PM, Jaehoon Chung <jh80.chung@xxxxxxxxxxx> wrote:
>>>> On 05/08/2014 06:40 PM, Yuvaraj Kumar wrote:
>>>>> Any comments on this patch?
>>>>>
>>>>> On Wed, Mar 26, 2014 at 5:16 PM, Yuvaraj Kumar C D <yuvaraj.cd@xxxxxxxxx> wrote:
>>>>>> From: Sonny Rao <sonnyrao@xxxxxxxxxxxx>
>>>>>>
>>>>>> This patch changes the fifo reset code to follow the reset procedure
>>>>>> outlined in the documentation of Synopsys  Mobile storage host databook
>>>>>> 7.2.13.
>>>>>> Without this patch, we could able to see eMMC was not detected after
>>>>>> multiple reboots due to driver hangs while eMMC tuning for HS200.
>>>>>>
>>>>>> Signed-off-by: Sonny Rao <sonnyrao@xxxxxxxxxxxx>
>>>>>> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@xxxxxxxxxxx>
>>>>>> ---
>>>>>>  drivers/mmc/host/dw_mmc.c |   48 ++++++++++++++++++++++++++++++++++++++++++++-
>>>>>>  drivers/mmc/host/dw_mmc.h |    1 +
>>>>>>  2 files changed, 48 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>>>>> index 32dd81d..1d77431 100644
>>>>>> --- a/drivers/mmc/host/dw_mmc.c
>>>>>> +++ b/drivers/mmc/host/dw_mmc.c
>>>>>> @@ -2220,7 +2220,53 @@ static inline bool dw_mci_fifo_reset(struct dw_mci *host)
>>>>>>                 host->sg = NULL;
>>>>>>         }
>>>>>>
>>>>>> -       return dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
>>>>>> +       /*
>>>>>> +        * The recommended method for resetting is to always reset the
>>>>>> +        * controller and the fifo, but differs slightly depending on the mode.
>>>>>> +        * Note that this doesn't handle the "generic DMA" (not IDMAC) case.
>>>>>> +        */
>>>>
>>>> "not IDMAC" is confused..
>>>>
>>>
>>> The documentation describes three different possible modes.  There's a
>>> mode that doesn't use IDMAC but still does DMA.  But as far as I can
>>> tell this driver doesn't support that way.  We can just remove that
>>> wording if it's confusing.
>
> How did it know whether dma is generic DMA or not?
>

That's a good question.  I wasn't sure whether the driver supported it
or not.  It looks like it definitely supports IDMAC through the
CONFIG_MMC_DW_IDMAC flag, but I wasn't sure if it was supported the
generic dma.  Maybe if CONFIG_MMC_DW_IDMAC isn't specified but
host->dma_ops is not NULL then we are using the generic dma mode.

>>>
>>>>>> +       if (dw_mci_ctrl_reset(host, SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET)) {
>>>>>> +               unsigned long timeout = jiffies + msecs_to_jiffies(500);
>>>>>> +               u32 status, rint;
>>>>>> +
>>>>>> +               /* if using dma we wait for dma_req to clear */
>>>>>> +               if (host->using_dma) {
>>>>>> +                       do {
>>>>>> +                               status = mci_readl(host, STATUS);
>>>>>> +                               if (!(status & SDMMC_STATUS_DMA_REQ))
>>>>>> +                                       break;
>>>>>> +                               cpu_relax();
>>>>>> +                       } while (time_before(jiffies, timeout));
>>>>>> +
>>>>>> +                       if (status & SDMMC_STATUS_DMA_REQ)
>>>>>> +                               dev_err(host->dev,
>>>>>> +                                       "%s: Timeout waiting for dma_req to "
>>>>>> +                                       "clear during reset", __func__);
>>>>>> +
>>>>>> +                       /* when using DMA next we reset the fifo again */
>>>>>> +                       dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
>>>>>> +               }
>>>>>> +               /*
>>>>>> +                * In all cases we clear the RAWINTS register to clear any
>>>>>> +                * interrupts.
>>>>>> +                */
>>>>>> +               rint = mci_readl(host, RINTSTS);
>>>>>> +               rint = rint & (~mci_readl(host, MINTSTS));
>> you use the "status or temp" instead of rint. (you can reuse the variable.)
>> And can use "status &= ~mci_readl(host,MINTSTS);"
>>
>>>>
>>>> Just clear the RINTSTS register? why do you add these?
>>>>
>>>
>>> This will look at what is not masked, and only clear those bits.
>> Well, i known if clear the RINTSTS register,
>> recommended to use "0xfffffff" and set the value for interrupt.
>
> Can be used "0xfffffff"?
>

Yeah we probably can.  We just lose information about interrupts that
were masked, but maybe we just don't care about any of them anyway, so
it doesn't matter.

> Best Regards,
> Jaehoon Chung
>>
>>>
>>>>>> +               if (rint)
>>>>>> +                       mci_writel(host, RINTSTS, rint);
>>>>>> +
>>>>>> +       } else
>>>>>> +               dev_err(host->dev, "%s: Reset bits didn't clear", __func__);
>>>>
>>>> Just display the error log? I didn't understand this.
>>>> If you displayed the error log, then it needs to return the error value.
>>>>
>>>>>> +
>>>>>> + #ifdef CONFIG_MMC_DW_IDMAC
>>>>>> +       /* It is also recommended that we reset and reprogram idmac */
>>>>>> +       dw_mci_idmac_reset(host);
>>>>>> + #endif
>>>>>> +
>>>>>> +       /* After a CTRL reset we need to have CIU set clock registers  */
>>>>>> +       mci_send_cmd(host->cur_slot, SDMMC_CMD_UPD_CLK, 0);
>>
>> Well, why do you send the clock update command?
>> I didn't see that update the value related with clock.
>>
>> Best Regards,
>> Jaehoon Chung
>>
>>>>>> +
>>>>>> +       return true;
>>>>>>  }
>>>>>>
>>>>>>  static inline bool dw_mci_ctrl_all_reset(struct dw_mci *host)
>>>>>> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
>>>>>> index 738fa24..037e47a 100644
>>>>>> --- a/drivers/mmc/host/dw_mmc.h
>>>>>> +++ b/drivers/mmc/host/dw_mmc.h
>>>>>> @@ -129,6 +129,7 @@
>>>>>>  #define SDMMC_CMD_INDX(n)              ((n) & 0x1F)
>>>>>>  /* Status register defines */
>>>>>>  #define SDMMC_GET_FCNT(x)              (((x)>>17) & 0x1FFF)
>>>>>> +#define SDMMC_STATUS_DMA_REQ           BIT(31)
>>>>>>  /* FIFOTH register defines */
>>>>>>  #define SDMMC_SET_FIFOTH(m, r, t)      (((m) & 0x7) << 28 | \
>>>>>>                                          ((r) & 0xFFF) << 16 | \
>>>>>> --
>>>>>> 1.7.10.4
>>>>>>
>>>>>
>>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux