From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH 1/1] fix i2c_msg.len not aligning with i2c_master_send Date: Thu, 4 Feb 2010 14:14:51 +0100 Message-ID: <20100204141451.3e0f865e@hyperion.delvare> References: <309424b61002032204y37307236q94ab3a502b0526e0@mail.gmail.com> <20100204103530.65429c04@hyperion.delvare> <309424b61002040438i2fae055dt2d3ef528eae99b48@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Eric Miao Cc: zhangfei gao , haojian.zhuang-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Linux I2C List-Id: linux-i2c@vger.kernel.org On Thu, 4 Feb 2010 04:47:41 -0800, Eric Miao wrote: > > How about return error in i2c_master_send & i2c_master_recv when count > > is bigger than 64K, as suggested by Ben. > > I think that's more preferable. Making the count parameter as u16, > though is going to generate a warning, yet that's usually ignored > by careless programmer, screaming out when this happens might > be more useful sometimes. Developers ignoring warnings get the pain the deserve. A check on "count" would come at the price of a small performance hit for every caller, even though in 99% of the cases the check isn't needed. That being said I don't care too much and will take whatever patch is sent to me. It would be a good idea to add a note about this limit in Documentation/i2c/writing-clients and/or include/linux/i2c.h. > > The device I used could receive 32K one time instead, the firmware > > download only takes place on-demand in fact. > > However, it took some time to debug, since no error info come out. > > Add error msg may notify users, though transfering more than 64K data > > one time is rarely happen. -- Jean Delvare