From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Subject: Re: [PATCH] mach-pxa/viper: Fix timeout usage for I2C
Date: Mon, 12 Apr 2010 21:13:19 +0200
Message-ID: <20100412211319.5a43c65b@hyperion.delvare>
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To: Eric Miao <eric.y.miao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>, Marc Zyngier <maz-20xNzvSXLT6hUMvJH42dtQ@public.gmane.org>, Paul Shen <paul.shen-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>, Mike Rapoport <mike-UTxiZqZC01RS1MOuV/RT9w@public.gmane.org>
List-Id: linux-i2c@vger.kernel.org

On Tue, 13 Apr 2010 01:57:51 +0800, Eric Miao wrote:
> On Sun, Apr 4, 2010 at 10:08 PM, Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>=
 wrote:
> > The timeout value is in jiffies, so it should be using HZ, not a pl=
ain
> > number. Assume '100' means 100ms here and adapt accordingly.
> >
> > Signed-off-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> > Cc: Eric Miao <eric.y.miao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > Cc: Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
> > Cc: Marc Zyngier <maz-20xNzvSXLT6hUMvJH42dtQ@public.gmane.org>
> > Cc: Paul Shen <paul.shen-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
> > Cc: Mike Rapoport <mike-UTxiZqZC01RS1MOuV/RT9w@public.gmane.org>
> > ---
> >
> > Janitorial fix, not tested due to no hardware.
> >
> > =C2=A0arch/arm/mach-pxa/viper.c | =C2=A0 =C2=A05 +++--
> > =C2=A01 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm/mach-pxa/viper.c b/arch/arm/mach-pxa/viper.c
> > index 1dd1334..c25921f 100644
> > --- a/arch/arm/mach-pxa/viper.c
> > +++ b/arch/arm/mach-pxa/viper.c
> > @@ -33,6 +33,7 @@
> > =C2=A0#include <linux/pm.h>
> > =C2=A0#include <linux/sched.h>
> > =C2=A0#include <linux/gpio.h>
> > +#include <linux/jiffies.h>
> > =C2=A0#include <linux/i2c-gpio.h>
> > =C2=A0#include <linux/serial_8250.h>
> > =C2=A0#include <linux/smc91x.h>
> > @@ -453,7 +454,7 @@ static struct i2c_gpio_platform_data i2c_bus_da=
ta =3D {
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0.sda_pin =3D VIPER_RTC_I2C_SDA_GPIO,
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0.scl_pin =3D VIPER_RTC_I2C_SCL_GPIO,
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0.udelay =C2=A0=3D 10,
> > - =C2=A0 =C2=A0 =C2=A0 .timeout =3D 100,
> > + =C2=A0 =C2=A0 =C2=A0 .timeout =3D HZ / 10,
> > =C2=A0};
> >
> > =C2=A0static struct platform_device i2c_bus_device =3D {
> > @@ -778,7 +779,7 @@ static void __init viper_tpm_init(void)
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0.sda_pin =3D=
 VIPER_TPM_I2C_SDA_GPIO,
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0.scl_pin =3D=
 VIPER_TPM_I2C_SCL_GPIO,
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0.udelay =C2=A0=
=3D 10,
> > - =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 .timeout =3D 100=
,
> > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 .timeout =3D HZ =
/ 10,
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0};
> > =C2=A0 =C2=A0 =C2=A0 =C2=A0char *errstr;
> >
>=20
> One other better and cleaner approach to such inconsistency issue is
> to have a timeout_ms field, and having i2c-gpio.c driver to convert t=
his
> to jiffies using msec_to_jiffies() at run-time.

With what benefit? Expressing time values in units of HZ is very
frequent in the kernel code and shouldn't actually surprise anyone.

--=20
Jean Delvare