Re: [PATCH] i2c-pcf8575: check for errors when accessing the chip

From: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
To: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: bart.vanassche-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org,
	hennerich-ZG0+EudsQA8dtHy/vicBwGD2FQJk+8+b@public.gmane.org
Subject: Re: [PATCH] i2c-pcf8575: check for errors when accessing the chip
Date: Thu, 15 May 2008 20:54:16 +0200	[thread overview]
Message-ID: <20080515205416.0a6bdaf9@hyperion.delvare> (raw)
In-Reply-To: <1210862127-9493-1-git-send-email-w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

Hi Wolfram,

On Thu, 15 May 2008 16:35:27 +0200, Wolfram Sang wrote:
> Make the driver check and report error cases when reading from or writing to
> the chip. It used to assume 'always success' and could even deliver bogus
> values.
> 
> Signed-off-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> ---
> 
> The PCF on my system seems broken, it does not respond (and I can't probe as my
> master doesn't support smbus_quick). The broken chip went unnoticed as the
> driver reported some (= bogus) values. So, I can only test the properly
> reported error cases, hopefully someone else can confirm the working case.
> (Michael and Bart, sorry for double post)
> 
>  drivers/i2c/chips/pcf8575.c |   29 +++++++++++++++++++++--------
>  1 files changed, 21 insertions(+), 8 deletions(-)

This driver is deprecated and you should be using
drivers/gpio/pcf857x.c instead if you can. That driver properly handles
I/O errors as far as I can see.

-- 
Jean Delvare

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