Re: [PATCH v6 0/8] power: add power sequence library

From: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
To: Peter Chen <hzpeterchen@gmail.com>
Cc: "Ulf Hansson" <ulf.hansson@linaro.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Peter Chen" <peter.chen@nxp.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Alan Stern" <stern@rowland.harvard.edu>,
	"Mark Brown" <broonie@kernel.org>,
	"Sebastian Reichel" <sre@kernel.org>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Dmitry Eremin-Solenikov" <dbaryshkov@gmail.com>,
	dwmw3@infradead.org, "Mark Rutland" <mark.rutland@arm.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"Krzysztof Kozłowski" <k.kozlowski@samsung.com>,
	"Linux USB List" <linux-usb@vger.kernel.org>,
	oscar@naiandei.net, "Paweł Moll" <pawel.moll@arm.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"Fabio Estevam" <festevam@gmail.com>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Stephen Boyd" <stephen.boyd@linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	troy.kisky@boundarydevices.com, stillcompiling@gmail.com,
	"Philipp Zabel" <p.zabel@pengutronix.de>,
	"Maciej S. Szmigiero" <mail@maciej.szmigiero.name>,
	mka@chromium.org,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v6 0/8] power: add power sequence library
Date: Mon, 19 Sep 2016 13:47:43 +0530	[thread overview]
Message-ID: <364c3aa6-024a-1df5-3ae0-cab0535aae73@linaro.org> (raw)
In-Reply-To: <20160919074637.GA10289@b29397-desktop>

On Monday 19 September 2016 01:16 PM, Peter Chen wrote:
> On Mon, Sep 19, 2016 at 01:09:10PM +0530, Vaibhav Hiremath wrote:
>>
>> On Friday 09 September 2016 02:17 PM, Ulf Hansson wrote:
>>> [...]
>>>
>>>>>>> We had an agreement that keep mmc's pwrseq framework unchanging.
>>>>>>> Unless Ulf and rob both agree to change.
>>>>>> Why 2 separate approach for same problem ?
>>>>>> And I see this as possible duplication of code/functionality :)
>>>>> How the new kernel compatibles old dts? If we do not need to
>>>>> consider this problem, the mmc can try to use power sequence library
>>>>> too in future.
>>>> I think we should attempt to get both MMC and USB power seq
>>>> come on one agreement, so that it can be reused.
>>> That would be nice. Although, to do that you would have to allow some
>>> DT bindings to be deprecated in the new generic power seq bindings, as
>>> otherwise you would break existing DTBs.
>>>
>>> I guess that is what Rob was objecting to!?
>> yeah, thats right.
>>
>> So lets adopt similar implementation for USB as well instead of
>> library, but keeping MMC untouched as of now.
>>
>> What I am trying to propose here is,
>>
>> Lets have power-sequence framework (similar to V1 of this series),
>> with,
>>
>> pwrseq: Core framework for power sequence.
>> pwrseq_generic/simple: for all generic control, like reset and clock
>> pwrseq_emmc: probably duplication of existing code - the idea
>>                            here is, all future code should be using this new
>>                            binding, so that we can deprecate the
>> drivers/mmc/core/pwrseq
>> pwrseq_arche: The usecase which I am dealing with today, which is more
>>                           complex in nature.
>>
>> Then the respective drivers can add their drivers (if needed) based on
>> complexity.
>>
>> comments ??
> The key point here is DT maintainer (Rob) doesn't agree with adding new node
> for power sequence at dts.
>

Hmmm.
We haven't heard from Rob lately especially after introduction of complex
usecases. I hope he would revisit on above proposal.

Thanks,
Vaibhav