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

[micky]

On 06/16/2014 08:40 PM, Ulf Hansson wrote:
> 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?
Yes.
> > 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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