From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754525AbbATQeT (ORCPT ); Tue, 20 Jan 2015 11:34:19 -0500 Received: from mail-ig0-f177.google.com ([209.85.213.177]:46774 "EHLO mail-ig0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754448AbbATQeQ (ORCPT ); Tue, 20 Jan 2015 11:34:16 -0500 Date: Tue, 20 Jan 2015 16:34:10 +0000 From: Lee Jones To: Javier Martinez Canillas Cc: Olof Johansson , Doug Anderson , Bill Richardson , Simon Glass , Gwendal Grignou , Jonathan Corbet , linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RESEND v2 3/7] mfd: cros_ec: Add cros_ec_lpc driver for x86 devices Message-ID: <20150120163410.GC30656@x1> References: <1420205572-2640-1-git-send-email-javier.martinez@collabora.co.uk> <1420205572-2640-4-git-send-email-javier.martinez@collabora.co.uk> <20150120081104.GT21886@x1> <54BE7B08.1010900@collabora.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54BE7B08.1010900@collabora.co.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 20 Jan 2015, Javier Martinez Canillas wrote: > Hello Lee, > > On 01/20/2015 09:11 AM, Lee Jones wrote: > > On Fri, 02 Jan 2015, Javier Martinez Canillas wrote: > > > >> From: Bill Richardson > >> > >> This adds the LPC interface to the Chrome OS EC. Like the > >> I2C and SPI drivers, this allows userspace access to the EC. > > > > I'm fairly certain that this is _not_ an MFD device. Please locate it > > to the proper subsystem (input?). > > > > Sorry, it wasn't my intention to use the mfd subsystem as a place to dump > random drivers. Is that I still find hard to understand what is the line > between what falls under mfd and what doesn't. > > For example, I see that mfd drivers are for devices which have multiple > functions and the mfd driver is the one that spawns the platform devices > and provide an interface to access the I/O registers used by the different > platform drivers of the sub-devices. > > So, the Embedded Controller driver (drivers/mfd/cros_ec.c) falls into that > category and in fact has been in the mfd driver for a long time. Now, if > an mfd device support different type of buses (e.g: i2c, spi, etc) I see > that both the core driver and the driver for the transport method are > in the drivers/mfd directory. As an example: > > drivers/mfd/arizona-{core,i2c,spi}.c > drivers/mfd/da9052-{core,i2c,spi}.c > drivers/mfd/mc13xxx-{core,i2c,spi}.c > drivers/mfd/tps65912-{core,i2c,spi}.c > drivers/mfd/wm831x-{core,i2c,spi,otp}.c > > In the cros_ec case, we already have drivers/mfd/cros_ec_{i2c,spi}.c so > since the Low Pin Count is another transport method I thought that this > driver belonged to the drivers/mfd directory. > > Now, all those drivers may be wrong and the buses don't belong to the mfd > subsystem but then I think we need to document that since it seems that is > the correct way to do it just by looking at the other drivers. I don't think the drivers you mentioned above do anything practical. For instance, they are not SPI/IC2/etc drivers. They should only offer some abstraction layers which are used to communicate with the device. The driver you are submitting looks a lot more like a device driver, which should live somewhere else. Don't ask me where though, I'm not even sure what a Low Pin Controller does. -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog