From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH] rtc-ds1307: True SMBus compatibility Date: Wed, 7 Jan 2009 16:27:09 +0100 Message-ID: <20090107162709.755982c0@hyperion.delvare> References: <1231177261.13443.20.camel@localhost.localdomain> <20090107142426.4be04d4d@hyperion.delvare> <9ae48b020901070722l77bebc6boc8fa2fd0bcc8da28@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <9ae48b020901070722l77bebc6boc8fa2fd0bcc8da28-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ed Swierk Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, David Brownell , Alessandro Zummo , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton , BARRE Sebastien List-Id: linux-i2c@vger.kernel.org Hi Ed, On Wed, 7 Jan 2009 07:22:12 -0800, Ed Swierk wrote: > On Wed, Jan 7, 2009 at 5:24 AM, Jean Delvare wrote: > > Are you certain the nForce2 controllers can't do it? The i2c-nforce2 > > driver doesn't implement it, but this doesn't mean the hardware can't > > do it. I don't have any datasheet for these chips, but I know their > > SMBus implementation is very similar to those of the AMD 8111, and > > i2c-amd8111 has support for I2C block reads and writes. I think it > > would be worth giving it a try, by copying the i2c-amd8111 > > implementation into the i2c-nforce2 driver and seeing if it happens to > > just work. If it works, that would be more elegant than your proposed > > hack to the rtc-ds1307 driver. > > I checked the datasheet and also tried every possible SMBus command > value to try to discover any supported commands that the i2c-nforce2 > driver happens not to use, to no avail. The nVidia SMBus is pure > SMBus. Did you try 0x4a (as i2c-amd8111 is using)? So, you have the datasheet... Is this something you would be allowed to share with me? > I could change the ds1307 driver to check whether the controller > supports i2c block commands and fall back to emulation only if they > are not available. Would that address your concerns? Yes, that would. Same thing the eeprom or lm93 drivers are doing, to only name a few of them. Should be fairly easy. -- Jean Delvare