linux-kernel - Re: [PATCH 1/2] regulator: pbias: use untranslated address to program pbias regulator

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Message-ID: <55D2C872.9000400@ti.com>
Date:	Tue, 18 Aug 2015 11:23:54 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Mark Brown <broonie@...nel.org>
CC:	<tony@...mide.com>, <lgirdwood@...il.com>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<grygorii.strashko@...com>, <nsekhar@...com>,
	<stable@...r.kernel.org>, Tero Kristo <t-kristo@...com>
Subject: Re: [PATCH 1/2] regulator: pbias: use untranslated address to program
 pbias regulator

Hi Mark Brown,

On Friday 14 August 2015 11:30 PM, Mark Brown wrote:
> On Mon, Jul 27, 2015 at 04:54:09PM +0530, Kishon Vijay Abraham I wrote:
> 
>> vsel_reg and enable_reg of the pbias regulator descriptor should actually
>> have the offset from syscon. However after the pbias device tree node
> 
> I'm having a hard time understanding this statement, sorry.  What makes
> you say that they "shouild actually have the offset from syscon"?  What
> is the problem that this is supposed to fix?

The register to program pbias regulator is 0x4A002E00. The syscon base address
is 0x4a002000. So the vsel_reg and enable_reg should have the offset from
syscon base address. regulator_enable_regmap gets the base address from
'regmap' and offset from 'enable_reg' in order to program the pbias regulator.

But without this patch vsel_reg and enable_reg have the absolute address
instead of just the offset.
> 
>> is moved as a child node of syscon, vsel_reg and enable_reg has the
>> absolute address because of the address translation that happens while
>> creating device from device tree node.
>> So avoid using platform_get_resource and use of_get_address in order to
>> get only the offset (untranslated address) and populate these in
>> vsel_reg and enable_reg.
> 
> This sounds like we're going in the wrong direction, we're moving from a
> more generic API to a firmware specific one.  Why is this a good fix?

platform_get_resource can be used if we need the absolute address but here we
need only the offset.

Thanks
Kishon
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