linux-kernel - Re: [PATCH v2] MediaTek PMIC support

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Date:	Thu, 29 Jan 2015 16:44:19 +0100
From:	Matthias Brugger <matthias.bgg@...il.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	Olof Johansson <olof@...om.net>, Arnd Bergmann <arnd@...db.de>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	YH Chen (陳昱豪) <yh.chen@...iatek.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Henry Chen <henryc.chen@...iatek.com>,
	Rob Herring <robh+dt@...nel.org>,
	Yingjoe Chen (陳英洲) 
	<Yingjoe.Chen@...iatek.com>,
	Eddie Huang <eddie.huang@...iatek.com>,
	Lee Jones <lee.jones@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	James Liao <jamesjj.liao@...iatek.com>,
	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH v2] MediaTek PMIC support

2015-01-29 15:27 GMT+01:00 Sascha Hauer <s.hauer@...gutronix.de>:
> On Thu, Jan 29, 2015 at 01:39:42PM +0100, Matthias Brugger wrote:
>> Hi Sascha,
>>
>> 2015-01-26 12:47 GMT+01:00 Sascha Hauer <s.hauer@...gutronix.de>:
>> > Olof, Arnd,
>> >
>> > OK to put the driver into drivers/soc/mediatek? Can you take these
>> > patches?
>>
>> How does this patches fit together with the one James clock framework patches?
>> Both use the same compatible "mediatek,mt8135-infracfg" and
>> "mediatek,mt8135-pericfg".
>>
>> I had a look on other implementations and they attach the reset
>> controller to the clk driver, if they share the same hw block.
>> Might we run into problems if we implement the clocks in the mfd, as
>> we need the clocks early in boot (e.g. for the timer)?
>
> From my experience the clocks are needed by the timer before any driver
> initializes.
>
>>
>> In mt6589 pericfg apart from the clocks and reset controller provides
>> registers for AXI bus control and USB wakeup and USB clock selection.
>> The infracfg block provides top AXI bus fabric control signals and
>> remap registers for the modem.
>> Mike, Stephen, what do you think. Can we implement the clk in a mfd
>> driver? Or do you prefer to implement the whole block in the clk
>> driver?
>
> Currently the clk support uses regular CLK_OF_DECLARE which handles the
> clock part of pericfg/infracfg and then later a regular driver for
> pericfg/infracfg comes and handles the rest of the functionality. Since
> both use separate registers in the device register space it should work
> fine.

It should work until some driver start to use request and map, as you
provide the whole register space.
If you want to implement drivers for pericfg/infracfg like this, why
don't you implement the reset controller in drivers/reset?

Anyway I'm not really happy with the solution of having several device
drivers for the same dts compatible string.

>
> Sascha
>
> --
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