[PATCH] i2c: at91: add a sanity check on i2c message length

[Wolfram Sang]

On Fri, Nov 02, 2012 at 12:04:45PM +0100, ludovic.desroches wrote:
> Hi Wolfram,
> 
> Le 11/01/2012 11:29 PM, Wolfram Sang a écrit :
> >On Wed, Oct 10, 2012 at 04:25:58PM +0200, ludovic.desroches at atmel.com wrote:
> >>From: Ludovic Desroches <ludovic.desroches at atmel.com>
> >>
> >>If the i2c message length is zero, i2c-at91 will directly return an error
> >>instead of trying to send a zero-length message.
> >>
> >>Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
> >
> >What happens if you send a 0 byte message? Some hardware is able to do
> >this and it will be used in SMBUS QUICK which the driver states to
> >support according to at91_twi_func().
> 
> Without this I had some data corruption when writing to / reading
> from a serial eeprom (depending on the IP version).
> 
> Yes SMBUS quick command is supported but is not managed in the
> driver, we have to tell explicitly the IP that we want to send this
> command.

Ok, so unless you want to implement the support, please update this
patch with a comment that SMBUS_QUICK is a TODO and remove the
SMBUS_QUICK capability.

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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