Re: [PATCH RESEND] x86, intel_mid: ADC management

From: Jonathan Cameron <jic23@cam.ac.uk>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>,
	mingo@elte.hu, linux-kernel@vger.kernel.org,
	Jonathan Cameron <jic23@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH RESEND] x86, intel_mid: ADC management
Date: Wed, 11 Apr 2012 13:55:27 +0100	[thread overview]
Message-ID: <4F857F3F.5080701@cam.ac.uk> (raw)
In-Reply-To: <20120411133035.25fa00b0@pyramind.ukuu.org.uk>

On 4/11/2012 1:30 PM, Alan Cox wrote:
>> needs to be abstracted as well.  Consumers might not care that the gain
>> just doubled because someone else requested it, but I suspect many of them will.
> At the bottom layer I'd expect a second consumer of the same data to get
> -EBUSY, but you are then going to tell me there are ADCs with one gain
> control for several channels no doubt 8)
yup.  If you can think of it, someone hardware guy will have implemented 
it! In this case
often comes down to the fact that most adcs are actually a mux on the 
front of a single
channel and the pga may be before the mux or after it (or for a laugh, 
sometimes both).

A real 'fun' one is devices that do scan reads.  That is you can only 
read certain combinations
of channels at a time and sometimes those combinations are far from 
obvious...
>
>
>> end up with most of IIO.  That's effectively what we did...   It's big
>> because there are
>> actually not that many 'simple' adc's out there.
> Fair enough - you would be the expert there.
I just wish they were all simple!