linux-kernel - Re: [PATCH RESEND v2 3/7] mfd: cros_ec: Add cros_ec

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Message-ID: <54C0DC2E.2030701@collabora.co.uk>
Date:	Thu, 22 Jan 2015 12:17:02 +0100
From:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
To:	Lee Jones <lee.jones@...aro.org>
CC:	Olof Johansson <olof@...om.net>,
	Doug Anderson <dianders@...omium.org>,
	Bill Richardson <wfrichar@...omium.org>,
	Simon Glass <sjg@...gle.com>,
	Gwendal Grignou <gwendal@...gle.com>,
	Jonathan Corbet <corbet@....net>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	arnd@...db.de
Subject: Re: [PATCH RESEND v2 3/7] mfd: cros_ec: Add cros_ec_lpc driver for
 x86 devices

Hello Lee,

On 01/22/2015 11:56 AM, Lee Jones wrote:
>> >
>> Yes, I completely understand your point, is that I didn't think that a ~300
>> lines driver was that bad specially since the communication bits that reads
>> and writes the register is not a complex logic IMHO.
> 
> This has nothing to do with LoC, it's the principle of the matter.
>

Ok, got it.
 
>> >> > Are there any other Low Pin Count drivers in the kernel?
>> >> >
>> >> 
>> >> I don't know tbh, I didn't even know what LPC was before I picked this patch
>> >> to push it upstream. I searched in the Linux codebase for other LPC drivers
>> >> but I didn't find anything, that doesn't mean that it doesn't exist though.
>> > 
>> > I agree.  Perhaps a suitable driver should live in drivers/misc until
>> > there are enough of them to warrant its own subsystem.
>> >
>> 
>> Yes, I can move the driver to drivers/misc if you think that is more suitable
>> to be there.
>> 
>> I've taken another look and AFAICT there are two other mfd drivers that use an
>> LPC bus, these are drivers/mfd/lpc_{i,s}ch.c for Intel's I/O Controller HUB and 
>> System Controller Hub respectively.
> 
> These looked like PCI aggregates when I looked at them last?
> 

Yes, it seems the LPC bus is behind a PCI bus on these chips. Or at least
that's what I understood on a quick read to the Intel SCH datasheet [0].

Now going back to the Cros EC LPC driver, you are right that this may not
be suitable to drivers/mfd so I'll move it to drivers/misc instead.

Thanks a lot for your feedback.

Best regards,
Javier

[0]: http://www.intel.com/content/www/us/en/intelligent-systems/menlow/sch-datasheet.html
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