Re: [PATCH V3] mmc:core: Avoid useless detecting task when card is busy

[Zhang Haijun <b42677@freescale.com>]

Hi, Ulf

Kindly refer to my inline comment.


于 2013/9/24 16:41, Ulf Hansson 写道:
> Hi Haijun,
>
>
> On 24 September 2013 05:42, Zhang Haijun <b42677@freescale.com> wrote:
>> Hi, Ulf
>>
>> I had update the patch according to your suggestion.
>> I test on my platform during last night.
>> About 200G random continuous data was written to 32G SDHC Card.
>> No call trace was encountered.
>> I think it can meet with your demand and solve the problem.
> Sounds promising. :-)
>
>>
>> 于 2013/9/24 10:08, Haijun Zhang 写道:
>>> When card is in cpu polling mode to detect card present. Card detecting
>>> task will be scheduled about once every second. When card is busy in large
>>> file transfer, detecting task will be hang and call trace will be prompt.
>>> When handling the request, CMD13 is always followed by every command when
>>> it was complete. So assume that card is present to avoid this duplicate
>>> detecting. Only polling card when card is free to reduce conflict with
>>> data transfer.
>>>
>>> <7>mmc0: req done (CMD13): 0: 00000e00 00000000 00000000 00000000
>>> INFO: task kworker/u:1:12 blocked for more than 120 seconds.
>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>> kworker/u:1     D 00000000     0    12      2 0x00000000
>>> Call Trace:
>>> [ee06dd50] [44042028] 0x44042028
>>> (unreliable)
>>> [ee06de10] [c0007a0c] __switch_to+0xa0/0xf0
>>> [ee06de30] [c04dd50c] __schedule+0x1f8/0x4a4
>>>
>>> [ee06dea0] [c04dd898] schedule+0x30/0xbc
>>>
>>> [ee06deb0] [c03816a4] __mmc_claim_host+0x98/0x19c
>>>
>>> [ee06df00] [c0385f88] mmc_sd_detect+0x38/0xc0
>>>
>>> [ee06df10] [c0382b0c] mmc_rescan+0x294/0x2e0
>>> [ee06df40] [c00661cc] process_one_work+0x140/0x3e0
>>>
>>> [ee06df70] [c0066bf8] worker_thread+0x18c/0x36c
>>> [ee06dfb0] [c006bf10] kthread+0x7c/0x80
>>>
>>> [ee06dff0] [c000de58] kernel_thread+0x4c/0x68
>>> <7>sdhci [sdhci_irq()]: *** mmc0 got interrupt: 0x00000001
>>>
>>> Signed-off-by: Haijun Zhang <haijun.zhang@freescale.com>
>>> ---
>>> changes for V3:
>>>        - Remove mmc_try_claim_host.
>>> changes for V2:
>>>        - Add card detecting once the last request is done.
>>>
>>>   drivers/mmc/card/block.c | 29 +++++++++++++++++++++++++++--
>>>   drivers/mmc/core/mmc.c   |  5 +++++
>>>   drivers/mmc/core/sd.c    |  5 +++++
>>>   drivers/mmc/core/sdio.c  |  5 +++++
>>>   4 files changed, 42 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>>> index 1a3163f..d1f1730 100644
>>> --- a/drivers/mmc/card/block.c
>>> +++ b/drivers/mmc/card/block.c
>>> @@ -1960,9 +1960,21 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>>>        struct mmc_host *host = card->host;
>>>        unsigned long flags;
>>>
>>> -     if (req && !mq->mqrq_prev->req)
>>> +     if (req && !mq->mqrq_prev->req) {
>>> +             /*
>>> +              * When we are here, card polling task will be blocked.
>>> +              * So disable it to avoid this useless schedule.
>>> +              */
>>> +             if (host->caps & MMC_CAP_NEEDS_POLL) {
>>> +                     spin_lock_irqsave(&host->lock, flags);
>>> +                     host->rescan_disable = 1;
>>> +                     spin_unlock_irqrestore(&host->lock, flags);
>>> +                     cancel_delayed_work(&host->detect);
>>> +             }
>>> +
>>>                /* claim host only for the first request */
>>>                mmc_get_card(card);
>>> +     }
>>>
>>>        ret = mmc_blk_part_switch(card, md);
>>>        if (ret) {
>>> @@ -1999,7 +2011,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>>>
>>>   out:
>>>        if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
>>> -          (req && (req->cmd_flags & MMC_REQ_SPECIAL_MASK)))
>>> +                     (req && (req->cmd_flags & MMC_REQ_SPECIAL_MASK))) {
>>>                /*
>>>                 * Release host when there are no more requests
>>>                 * and after special request(discard, flush) is done.
>>> @@ -2007,6 +2019,19 @@ out:
>>>                 * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
>>>                 */
>>>                mmc_put_card(card);
>>> +
>>> +             /*
>>> +              * Detecting card status immediately in case card being
>>> +              * removed just after the request is complete.
>>> +              */
>>> +             if (host->caps & MMC_CAP_NEEDS_POLL) {
>>> +                     spin_lock_irqsave(&host->lock, flags);
>>> +                     host->rescan_disable = 0;
>>> +                     spin_unlock_irqrestore(&host->lock, flags);
>>> +                     mmc_detect_change(host, 0);
>>> +             }
>>> +     }
>>> +
>>>        return ret;
>>>   }
>>>
>>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>>> index 6d02012..4bdf68c 100644
>>> --- a/drivers/mmc/core/mmc.c
>>> +++ b/drivers/mmc/core/mmc.c
>>> @@ -1443,6 +1443,7 @@ static int mmc_alive(struct mmc_host *host)
>>>   static void mmc_detect(struct mmc_host *host)
>>>   {
>>>        int err;
>>> +     unsigned long flags;
>>>
>>>        BUG_ON(!host);
>>>        BUG_ON(!host->card);
>>> @@ -1457,6 +1458,10 @@ static void mmc_detect(struct mmc_host *host)
>>>        mmc_put_card(host->card);
>>>
>>>        if (err) {
>>> +             spin_lock_irqsave(&host->lock, flags);
>>> +             host->rescan_disable = 0;
>>> +             spin_unlock_irqrestore(&host->lock, flags);
>>> +
>>>                mmc_remove(host);
>>>
>>>                mmc_claim_host(host);
>>> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
>>> index 5e8823d..c87203c 100644
>>> --- a/drivers/mmc/core/sd.c
>>> +++ b/drivers/mmc/core/sd.c
>>> @@ -1041,6 +1041,7 @@ static int mmc_sd_alive(struct mmc_host *host)
>>>   static void mmc_sd_detect(struct mmc_host *host)
>>>   {
>>>        int err;
>>> +     unsigned long flags;
>>>
>>>        BUG_ON(!host);
>>>        BUG_ON(!host->card);
>>> @@ -1055,6 +1056,10 @@ static void mmc_sd_detect(struct mmc_host *host)
>>>        mmc_put_card(host->card);
>>>
>>>        if (err) {
>>> +             spin_lock_irqsave(&host->lock, flags);
>>> +             host->rescan_disable = 0;
>>> +             spin_unlock_irqrestore(&host->lock, flags);
>>> +
>>>                mmc_sd_remove(host);
>>>
>>>                mmc_claim_host(host);
>>> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
>>> index 80d89cff..a59e34b 100644
>>> --- a/drivers/mmc/core/sdio.c
>>> +++ b/drivers/mmc/core/sdio.c
>>> @@ -862,6 +862,7 @@ static int mmc_sdio_alive(struct mmc_host *host)
>>>   static void mmc_sdio_detect(struct mmc_host *host)
>>>   {
>>>        int err;
>>> +     unsigned long flags;
>>>
>>>        BUG_ON(!host);
>>>        BUG_ON(!host->card);
>>> @@ -900,6 +901,10 @@ static void mmc_sdio_detect(struct mmc_host *host)
>>>
>>>   out:
>>>        if (err) {
>>> +             spin_lock_irqsave(&host->lock, flags);
>>> +             host->rescan_disable = 0;
>>> +             spin_unlock_irqrestore(&host->lock, flags);
>>> +
>>>                mmc_sdio_remove(host);
>>>
>>>                mmc_claim_host(host);
> Re-enabling the rescan, like "host->rescan_disable = 0" shall be done
> from mmc_detect_card_removed function instead of from mmc_detect,
> mmc_sd_detect mmc_sdio_detect.
>
> Look into the mmc_detect_card_removed and where specific error
> handling is done for MMC_CAP_NEEDS_POLL.
Thanks, Ulf

Whether the detect task need to be scheduled was decided in 
mmc_detect_card_removed function.
I enable rescan_disable here, just make sure the rescan task can be 
scheduled next time before card was
really removed.

Both interrupt mode and polling mode need the detect task to setup the 
card for the fist time.

Or I miss something? :-)
>
> Kind regards
> Ulf Hansson
>
>> --
>> Thanks & Regards
>> Haijun.
>>
>>

-- 
Thanks & Regards
Haijun.