linux-kernel - Re: [PATCH 07/12] mfd: syscon: Consider platform data a regmap config name

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Message-ID: <1392205398.848.10.camel@hornet>
Date:	Wed, 12 Feb 2014 11:43:18 +0000
From:	Pawel Moll <pawel.moll@....com>
To:	Alexander Shiyan <shc_work@...l.ru>
Cc:	Lee Jones <lee.jones@...aro.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/12] mfd: syscon: Consider platform data a regmap
 config name

On Wed, 2014-02-12 at 11:27 +0000, Alexander Shiyan wrote:
> Yeah, I gave up the idea to use the syscon_ids[] to separate devices for
> non-DT case.
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/mfd/syscon.c?id=5104d2656d4874c51868dc7182016e9501ec99ca
> Instead, I use a hard definition for pdev->id, so that the names of
> syscon-devices are different and can be obtained from the driver
> it uses with syscon_regmap_lookup_by_pdevname().

It is a sort-of-solution (I personally dislike magic numbers, but this
is a separate discussion) for a completely-non-DT case, where you can
guarantee limited number of syscon devices.

In my case I have a DT system, where some of the MFD devices *may*
register syscon cells... No way to enforce ordering.

> I understand this topic correct?

The main idea here is to attach a meaningful label to the syscon
regmaps. My example:

/ # ls -d1 /sys/kernel/debug/regmap/syscon.*
/sys/kernel/debug/regmap/syscon.0.auto
/sys/kernel/debug/regmap/syscon.4.auto
/sys/kernel/debug/regmap/syscon.5.auto

vs

/ # ls -d /sys/kernel/debug/regmap/syscon.*
/sys/kernel/debug/regmap/syscon.0.auto-sys_id
/sys/kernel/debug/regmap/syscon.4.auto-sys_misc
/sys/kernel/debug/regmap/syscon.5.auto-sys_procid

Of course one could also define syscon_regmap_lookup_by_label() (I don't
really need it right now so didn't go that way)

Pawel

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