Re: [PATCH] net: dsa: b53: Replace mdelay with msleep in b53_switch_reset_gpio

[Jia-Ju Bai]

On 2018/4/12 0:19, Florian Fainelli wrote:
> On 04/11/2018 12:14 AM, Jia-Ju Bai wrote:
> > On 2018/4/11 13:30, Phil Reid wrote:
> > > On 11/04/2018 09:51, Jia-Ju Bai wrote:
> > > > b53_switch_reset_gpio() is never called in atomic context.
> > > >
> > > > The call chain ending up at b53_switch_reset_gpio() is:
> > > > [1] b53_switch_reset_gpio() <- b53_switch_reset() <-
> > > >      b53_reset_switch() <- b53_setup()
> > > >
> > > > b53_switch_reset_gpio() is set as ".setup" in struct dsa_switch_ops.
> > > > This function is not called in atomic context.
> > > >
> > > > Despite never getting called from atomic context,
> > > > b53_switch_reset_gpio()
> > > > calls mdelay() to busily wait.
> > > > This is not necessary and can be replaced with msleep() to
> > > > avoid busy waiting.
> > > >
> > > > This is found by a static analysis tool named DCNS written by myself.
> > > > And I also manually check it.
> > > >
> > > > Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
> > > > ---
> > > >    drivers/net/dsa/b53/b53_common.c | 4 ++--
> > > >    1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/net/dsa/b53/b53_common.c
> > > > b/drivers/net/dsa/b53/b53_common.c
> > > > index 274f367..e070ff6 100644
> > > > --- a/drivers/net/dsa/b53/b53_common.c
> > > > +++ b/drivers/net/dsa/b53/b53_common.c
> > > > @@ -597,10 +597,10 @@ static void b53_switch_reset_gpio(struct
> > > > b53_device *dev)
> > > >        /* Reset sequence: RESET low(50ms)->high(20ms)
> > > >         */
> > > >        gpio_set_value(gpio, 0);
> > > > -    mdelay(50);
> > > > +    msleep(50);
> > > >          gpio_set_value(gpio, 1);
> > > > -    mdelay(20);
> > > > +    msleep(20);
> > > >          dev->current_page = 0xff;
> > > >    }
> > > Would that also imply gpio_set_value could be gpio_set_value_cansleep?
> > Yes, I think gpio_set_value_cansleep() is okay here?
> > Do I need to send a V2 patch to replace gpio_set_value()?
> Yes, I would lump these two changes in the same patch since this is
> effectively about solving sleeping vs. non sleeping operations.

Okay, I have sent a V2 patch, and you can have a look :)


Best wishes,
Jia-Ju Bai