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

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Date:   Wed, 22 Dec 2021 10:25:30 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
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

On Wed, Dec 22, 2021 at 09:01:03AM +0000, Lad, Prabhakar wrote:
> 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.

Yes please explain why this change is ok, not just that it is a random
compiler warning cleanup.

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

Please do.

thanks,

greg k-h