From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [RFC: 2.6 patch] remove the i2c-at91.c driver Date: Thu, 4 Sep 2008 12:18:49 -0700 Message-ID: <200809041218.49604.david-b@pacbell.net> References: <20080831161005.GC3695@cs181140183.pp.htv.fi> <20080902101127.GJ2716@fluff.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: i2c-bounces-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org Errors-To: i2c-bounces-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org To: Andrew Victor Cc: i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org, Ben Dooks List-Id: linux-i2c@vger.kernel.org On Thursday 04 September 2008, Andrew Victor wrote: > > I don't actually have G20 hardware to test it on, but until > somebody/Atmel have verified if this driver works or not, I'd prefer > to just to leave it as broken. > If it still doesn't work, then just remove all references to the driver. Right ... Note that resolving the lack of support for repeated starts would require driver updates in any case. Some of which COULD have been done with existing hardware. ISTR a combined transaction could be done S addr W [A] byte1 [A] byte2 [A] byte3 [A] Sr addr R [A] [byte4] A [byte5] ... N P ... with up to three bytes in the write segment. Obviously that's not an arbitrary I2C transaction ... in fact, it'd best be handled (IMO) as an SMBus adapter not an I2C adapter. (So maybe a new driver would be appropriate...) But I recall the lack of flow control to be a bigger issue. The hardware liked to TX the next byte before it was loaded into the (single byte) TX fifo, and then complain that there was no byte there. And likewise, to RX the next byte before the previous one got removed. Or ... if that's not what it was doing, it sure acted like it was! Now, *THOSE* issues seem highly amenable to hardware-only fixes: just stretch the clock until the FIFO is ready. - Dave _______________________________________________ i2c mailing list i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org http://lists.lm-sensors.org/mailman/listinfo/i2c