linux-kernel - Re: [PATCH v3 0/3] Qualcomm Resource Power Manager driver

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Date:	Thu, 19 Jun 2014 09:25:48 +0530
From:	Jassi Brar <jaswinder.singh@...aro.org>
To:	Kevin Hilman <khilman@...aro.org>
Cc:	Kumar Gala <galak@...eaurora.org>, Bjorn Andersson <bjorn@...o.se>,
	Lee Jones <lee.jones@...aro.org>,
	Bjorn Andersson <bjorn.andersson@...ymobile.com>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Josh Cartwright <joshc@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	Paul Walmsley <paul@...an.com>
Subject: Re: [PATCH v3 0/3] Qualcomm Resource Power Manager driver

On 18 June 2014 22:14, Kevin Hilman <khilman@...aro.org> wrote:
> Kumar Gala <galak@...eaurora.org> writes:
>
>> On Jun 18, 2014, at 10:53 AM, Kevin Hilman <khilman@...aro.org> wrote:
>>
>>> Bjorn Andersson <bjorn@...o.se> writes:
>>>
>>>> On Tue, Jun 17, 2014 at 10:07 AM, Kevin Hilman <khilman@...aro.org> wrote:
>>>>> +Paul Walmsley
>>>>>
>>>>> Bjorn Andersson <bjorn.andersson@...ymobile.com> writes:
>>>>>
>>>>>> This series adds a regulator driver for the Resource Power Manager found in
>>>>>> Qualcomm 8660, 8960 and 8064 based devices.
>>>>>>
>>>>>> The RPM driver exposes resources to its child devices, that can be accessed to
>>>>>> implement drivers for the regulators, clocks and bus frequency control that's
>>>>>> owned by the RPM in these devices.
>>>>>>
>>>>>> Changes since v2:
>>>>>>  - Fix copy-paste error in dt binding
>>>>>>  - Correct incomplete move from mfd to soc
>>>>>>  - Correct const mistake in regulator driver
>>>>>>
>>>>>> Changes since v1:
>>>>>>  - Moved rpm driver to drivers/soc
>>>>>
>>>>> I'm not sure I follow the motivation for having this under drivers/soc?
>>>>>
>>>> Hi Kevin,
>>>>
>>>> I've made the argument that to me this is conceptually a black box
>>>> handling regulators, clocks and other stuff; hence similar to a PMIC,
>>>> which would fit nicely into drivers/mfd.
>>>>
>>>> I still think this is the case and now that I look back I didn't get
>>>> any pushback from Lee Jones so maybe the move was premature?
>>>
>>> Yes, IMO, the move was premature, but hopefully the drivers/soc folks
>>> can chime in an clarify the criteria for inclusion there.
>>>
>>> Kevin
>>
>> I dont agree, I think having this in drivers/soc means that we can
>> clearly go through drivers/soc in the future and look for patterns
>> across SoCs that should be re-factored.
>
> I don't believe that was the goal in creating drivers/soc.
>
>> Where MFD seems like its become the new drivers misc.
>
> Well, I don't think that drivers/soc wants to be the new drivers/misc
> either. ;)
>
> Thinking more about what this RPM driver actually does, and since you
> mentioned patterns across SoCs, it seems to me the RPM driver bascially
> just doing the IPC.
>
> So, rather than MFD or drivers/soc, it seems to me that it should be
> implmented as a controller in the new common mailbox framwork[1] being
> worked on by Jassi Brar (added to Cc.)
>
> IIUC, RPM is actually only doing one-way IPC (it only exposes a write()
> interface to clients) so it seems like a rather simple implementation of
> a mailbox controller.
>
Yup, qcom_rpm.c is exactly what drivers/mailbox/ is meant for.

 Agreed the driver is _very_ SoC specific (Qualcomm) but so is any
other mailbox driver in my knowledge. So either we move all to
drivers/mailbox/ or empty that out into drivers/soc/   I tend to lean
towards the first option.

Thanks
-Jassi
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