Re: [PATCH RFC v6 2/9] PM / devfreq: Add generic imx bus scaling driver

From: Martin Kepplinger <martink@posteo.de>
To: Leonard Crestez <leonard.crestez@nxp.com>,
	Angus Ainslie <angus@akkea.ca>, Jacky Bai <ping.bai@nxp.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
	"Artur Świgoń" <a.swigon@partner.samsung.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Michael Turquette" <mturquette@baylibre.com>,
	"Marco Felsch" <m.felsch@pengutronix.de>,
	"linux-pm-owner@vger.kernel.org" <linux-pm-owner@vger.kernel.org>,
	"Alexandre Bailon" <abailon@baylibre.com>,
	"Matthias Kaehlcke" <mka@chromium.org>,
	"Abel Vesa" <abel.vesa@nxp.com>,
	"Anson Huang" <anson.huang@nxp.com>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Chanwoo Choi" <cw00.choi@samsung.com>,
	"MyungJoo Ham" <myungjoo.ham@samsung.com>,
	dl-linux-imx <linux-imx@nxp.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Silvano Di Ninno" <silvano.dininno@nxp.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"Aisheng Dong" <aisheng.dong@nxp.com>,
	"Saravana Kannan" <saravanak@google.com>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"Kyungmin Park" <kyungmin.park@samsung.com>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"Fabio Estevam" <fabio.estevam@nxp.com>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Georgi Djakov" <georgi.djakov@linaro.org>
Subject: Re: [PATCH RFC v6 2/9] PM / devfreq: Add generic imx bus scaling driver
Date: Thu, 13 Feb 2020 11:53:29 +0100	[thread overview]
Message-ID: <671afc9c-66d0-03d5-c810-ffb4e4ad76d7@posteo.de> (raw)
In-Reply-To: <9a8dac5b-25c0-7dca-8c25-9796ba2b4df5@posteo.de>

On 04.02.20 10:45, Martin Kepplinger wrote:
> On 20.11.19 19:02, Leonard Crestez wrote:
>> On 20.11.2019 18:38, Angus Ainslie wrote:
>>> On 2019-11-20 08:30, Leonard Crestez wrote:
>>>> On 20.11.2019 17:41, Angus Ainslie wrote:
>>>>> Hi Leonard,
>>>>>
>>>>> On 2019-11-20 07:04, Leonard Crestez wrote:
>>>>>> On 20.11.2019 16:08, Angus Ainslie wrote:
>>>>>> Is "mainline ATF" an important criteria for Purism?
>>>>>
>>>>> Yes we intend to bring all of our patches to mainline and were hoping
>>>>> that NXP would be doing the same. Shouldn't a mainline kernel run on a
>>>>> mainline ATF ?
>>>>
>>>> You can still use mainline ATF (tested right now) but the imx8m-ddrc
>>>> driver won't probe.
>>>
>>> Sorry I was talking about the DDR frequency scaling specifically. >
>>>> The ability to mix and match different branches of firmware and kernel
>>>> is very useful for testing. There might be slight incompatibilities but
>>>> in theory if a feature depends on both firmware and kernel support then
>>>> it should gracefully degrade rather than crash or hang.
>>>
>>> I saw the check you put in for the correct ATF version and that's very
>>> helpful thanks.
>>>
>>>> ATF support for this feature will be mainlined eventually, I picked the
>>>> linux side first because review is more challenging and changes are
>>>> much larger relative to what we have in our internal tree.
>>>
>>> Do you have a patch against mainline ATF that we can test this feature
>>> with ?
>>
>> Not right now, and imx atf is based on a slightly older version so some 
>> porting effort might be required.
>>
> 
> Hi Leonard,
> 
> Have you, by chance, looked at the mainline ATF side for your devfreq
> work in the meantime? I'd happily test. (btw. the linux driver fails
> "nicely" there.)
> 

hi again. Do you have any plans regarding the ATF implementation of
IMX_SIP_DDR_DVFS in mainline yet? The kernel is only one half of the
devfreq solution after all. I'm asking just to schedule my work a bit :)

thanks,
                            martin