Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 1 Nov 2022 01:08:33 +0100
From:   Sebastian Reichel <sebastian.reichel@collabora.com>
To:     Samuel Holland <samuel@sholland.org>
Cc:     Ondrej Jirman <megi@xff.cz>,
        "open list:POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS" 
        <linux-pm@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        linux-rockchip@lists.infradead.org
Subject: Re: [PATCH] power: supply: ip5xxx: Fix integer overflow in
 current_now calculation
Message-ID: <20221101000833.hwuhc7ki6b33fnhf@mercury.elektranox.org>
References: <20221028224052.293693-1-megi@xff.cz>
 <6b23af14-340d-b7b5-7d20-14fae03f724c@sholland.org>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="7sslbaiyftedhb4w"
Content-Disposition: inline
In-Reply-To: <6b23af14-340d-b7b5-7d20-14fae03f724c@sholland.org>
Precedence: bulk


--7sslbaiyftedhb4w
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

Hi,

On Fri, Oct 28, 2022 at 06:06:07PM -0500, Samuel Holland wrote:
> On 10/28/22 17:40, Ondrej Jirman wrote:
> > When current is larger than ~2A, the multiplication in current_now
> > property overflows and the kernel reports invalid negative current
> > value. Change the numerator and denominator while preserving their
> > ratio to allow up to +-6A before the overflow.
> >=20
> > Fixes: 75853406fa27 ("power: supply: Add a driver for Injoinic power ba=
nk ICs")
> > Signed-off-by: Ondrej Jirman <megi@xff.cz>
>=20
> Reviewed-by: Samuel Holland <samuel@sholland.org>
>=20
> > ---
> >  drivers/power/supply/ip5xxx_power.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >=20
> > diff --git a/drivers/power/supply/ip5xxx_power.c b/drivers/power/supply=
/ip5xxx_power.c
> > index 02ee4d252a3e..f39cb2f7aa11 100644
> > --- a/drivers/power/supply/ip5xxx_power.c
> > +++ b/drivers/power/supply/ip5xxx_power.c
> > @@ -398,7 +398,7 @@ static int ip5xxx_battery_get_property(struct power=
_supply *psy,
> >  		ret =3D ip5xxx_battery_read_adc(ip5xxx, IP5XXX_BATIADC_DAT0,
> >  					      IP5XXX_BATIADC_DAT1, &raw);
> > =20
> > -		val->intval =3D DIV_ROUND_CLOSEST(raw * 745985, 1000);
> > +		val->intval =3D DIV_ROUND_CLOSEST(raw * 261095, 350);
>=20
> DIV_ROUND_CLOSEST(raw * 149197, 200) would be marginally more accurate,
> but it doesn't matter in practice.

Thanks, I queued it with that change included.

-- Sebastian

>=20
> >  		return 0;
> > =20
> >  	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
>=20

--7sslbaiyftedhb4w
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=s9pm
-----END PGP SIGNATURE-----

--7sslbaiyftedhb4w--