linux-kernel - Re: [PATCH] watchdog: dw: use devm_watchdog_register

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Date:   Fri, 25 Jan 2019 08:17:03 +0000
From:   Jisheng Zhang <Jisheng.Zhang@...aptics.com>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] watchdog: dw: use devm_watchdog_register_device()

Hi,

On Fri, 25 Jan 2019 00:04:25 -0800 Guenter Roeck wrote:

> Hi,
> 
> On 1/24/19 11:52 PM, Jisheng Zhang wrote:
> > Use devm_watchdog_register_device() to simplify the code.
> > 
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
> > ---
> >   drivers/watchdog/dw_wdt.c | 3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> > index 501aebb5b81f..c053c2de5c2f 100644
> > --- a/drivers/watchdog/dw_wdt.c
> > +++ b/drivers/watchdog/dw_wdt.c
> > @@ -303,7 +303,7 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
> >   
> >   	watchdog_set_restart_priority(wdd, 128);
> >   
> > -	ret = watchdog_register_device(wdd);
> > +	ret = devm_watchdog_register_device(wdd);
> >   	if (ret)
> >   		goto out_disable_clk;
> >   
> > @@ -318,7 +318,6 @@ static int dw_wdt_drv_remove(struct platform_device *pdev)
> >   {
> >   	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
> >   
> > -	watchdog_unregister_device(&dw_wdt->wdd);
> >   	reset_control_assert(dw_wdt->rst);
> >   	clk_disable_unprepare(dw_wdt->clk);
> >   
> >   
> Unfortunately it isn't that easy. The other two calls have to be executed after
> unregistering the watchdog, meaning you would have to add devm_add_action()
> in the probe function to call them.

do you mean reset_control_asser() and the clk_disable_unprepare()? If yes,
does unregister the watchdog could trigger any register access? Per my
understanding, there's no register access path in the unregister. Am I
missing somthing?

Thanks