linux-kernel - Re: [PATCH] usb: renesas_usbhs: Fix unused variable warning

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Date:   Wed, 22 Dec 2021 09:01:03 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        USB list <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: renesas_usbhs: Fix unused variable warning

Hi Greg,

Thank you for the review.

On Wed, Dec 22, 2021 at 6:10 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Tue, Dec 21, 2021 at 05:15:32PM +0000, Lad Prabhakar wrote:
> > This patch fixes the below warning:
> >
> > drivers/usb/renesas_usbhs/mod.c: In function 'usbhs_status_get_each_irq':
> > drivers/usb/renesas_usbhs/mod.c:195:13: warning: variable 'intenb0'
> > set but not used [-Wunused-but-set-variable]
> >   195 |         u16 intenb0, intenb1;
> >       |
> >
> > Fixes: 33e4245ee919 ("usb: renesas_usbhs: Use platform_get_irq() to get the interrupt")
> > Reported-by: kernel test robot <lkp@...el.com>
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> >  drivers/usb/renesas_usbhs/mod.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/renesas_usbhs/mod.c b/drivers/usb/renesas_usbhs/mod.c
> > index f2ea3e1412d2..3919e350b487 100644
> > --- a/drivers/usb/renesas_usbhs/mod.c
> > +++ b/drivers/usb/renesas_usbhs/mod.c
> > @@ -192,13 +192,12 @@ static int usbhs_status_get_each_irq(struct usbhs_priv *priv,
> >                                    struct usbhs_irq_state *state)
> >  {
> >       struct usbhs_mod *mod = usbhs_mod_get_current(priv);
> > -     u16 intenb0, intenb1;
> >       unsigned long flags;
> > +     u16 intenb1;
> >
> >       /********************  spin lock ********************/
> >       usbhs_lock(priv, flags);
> >       state->intsts0 = usbhs_read(priv, INTSTS0);
> > -     intenb0 = usbhs_read(priv, INTENB0);
>
> Did you just break the hardware?  Reading is often times needed and
> clang has no idea about hardware issues.  We need proof in the changlog
> that this really is safe to do.
>
I introduced this warning in commit 33e4245ee919 ("usb: renesas_usbhs:
Use platform_get_irq() to get the interrupt'') where
IORESOURCE_IRQ_SHAREABLE flag handling was dropped and I missed to
remove this change. As a result I included a fixes tag for this
commit. Let me know if you want me to update the changelog.

> How did you test your change?
>
I haven't but can test it.

Cheers,
Prabhakar