Re: [PATCH 2/2] mmc: rtsx: add support for async request

[Ulf Hansson]

On 16 June 2014 11:09, micky <micky_ching@xxxxxxxxxxxxxx> wrote:
> On 06/16/2014 04:42 PM, Ulf Hansson wrote:
>>>
>>> @@ -36,7 +37,10 @@ struct realtek_pci_sdmmc {
>>> >         struct rtsx_pcr         *pcr;
>>> >         struct mmc_host         *mmc;
>>> >         struct mmc_request      *mrq;
>>> >+       struct workqueue_struct *workq;
>>> >+#define SDMMC_WORKQ_NAME       "rtsx_pci_sdmmc_workq"
>>> >
>>> >+       struct work_struct      work;
>>
>> I am trying to understand why you need a work/workqueue to implement
>> this feature. Is that really the case?
>>
>> Could you elaborate on the reasons?
>
> Hi Uffe,
>
> we need return as fast as possible in mmc_host_ops request(ops->request)
> callback,
> so the mmc core can continue handle next request.
> when next request everything is ready, it will wait previous done(if not
> done),
> then call ops->request().
>
> we can't use atomic context, because we use mutex_lock() to protect

ops->request should never executed in atomic context. Is that your concern?

> resource, and we have to hold the lock during handle request.
> So I use workq, we just queue a work and return in ops->request(),
> The mmc core can continue without blocking at ops->request().
>
> Best Regards.
> micky.

Kind regards
Uffe
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