linux-kernel - RE: [PATCH v5 2/2] mmc: Add mmc driver for Sunplus SP7021

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Date:   Fri, 1 Apr 2022 00:53:01 +0000
From:   Tony Huang 黃懷厚 <tony.huang@...plus.com>
To:     Arnd Bergmann <arnd@...db.de>
CC:     Tony Huang <tonyhuang.sunplus@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        "lhjeff911@...il.com" <lhjeff911@...il.com>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Wells Lu 呂芳騰 <wells.lu@...plus.com>,
        Lh Kuo 郭力豪 <lh.Kuo@...plus.com>
Subject: RE: [PATCH v5 2/2] mmc: Add mmc driver for Sunplus SP7021

Dear Arnd:

> <tony.huang@...plus.com> wrote:
> > > > +static void spmmc_request(struct mmc_host *mmc, struct
> > > > +mmc_request
> > > > +*mrq) {
> > > > +       struct spmmc_host *host = mmc_priv(mmc);
> > > > +       struct mmc_data *data;
> > > > +       struct mmc_command *cmd;
> > > > +       int ret;
> > > > +
> > > > +       ret = mutex_lock_interruptible(&host->mrq_lock);
> > > > +       if (ret)
> > > > +               return;
> > >
> > > I don't think it's valid to just return here when you get a signal.
> > > If nothing can handle the signal, doesn't it just hang?
> > >
> > > It also appears that you don't release the mutex until the tasklet
> > > runs, but it is not valid to release a mutex from a different context.
> > >
> > > You should get a warning about this when running a kernel with
> > > lockdep enabled at compile time. Please rework the locking to make this
> work.
> > >
> >         Reomve code:
> >     ret = mutex_lock_interruptible(&host->mrq_lock);
> >     if (ret)
> >          return;
> >
> >         Below is my modification:
> > .    mutex_lock(&host->mrq_lock);
> 
> That addresses the problem with the signal handling, but not the lock
> imbalance. Please fix that as well.

Ok, I will modify lock imbalance issue.

> > >
> > > It's better to use SYSTEM_SLEEP_PM_OPS/RUNTIME_PM_OPS instead of
> the
> > > SET_ version, then you can remove all the #ifdef checks.
> > >
> >
> >         I use SYSTEM_SLEEP_PM_OPS/RUNTIME_PM_OPS.
> >         Compile shows error. Error: implicit declaration of function ? ?
> SYSTEM_SLEEP_PM_OPS? ? Did you mean ? ? SET_SYSTEM_SLEEP_PM_OPS? ?
> [-Werror=implicit-function-declaration]
> 
> Maybe you are on an old kernel release?
> 

OK,I will use new kernel release to compiler.

> >         I reference other mmc driver.
> >         Below is my modification:
> >     Compiler is pass.
> >
> >         #ifdef CONFIG_PM_SLEEP
> >         static int spmmc_pm_suspend(struct device *dev)
> >         {
> >                 pm_runtime_force_suspend(dev);
> >
> >                 return 0;
> >         }
> 
> We should fix the other drivers as well. For the moment, just do it the right
> way now instead of copying the #ifdefs.
> 
OK, I will follow right way to remove #ifdef.