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

From: Angus Ainslie <angus@akkea.ca>
To: Leonard Crestez <leonard.crestez@nxp.com>
Cc: "Jacky Bai" <ping.bai@nxp.com>,
	"Marco Felsch" <m.felsch@pengutronix.de>,
	"Georgi Djakov" <georgi.djakov@linaro.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Chanwoo Choi" <cw00.choi@samsung.com>,
	"Artur Świgoń" <a.swigon@partner.samsung.com>,
	"Alexandre Bailon" <abailon@baylibre.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Anson Huang" <anson.huang@nxp.com>,
	"Abel Vesa" <abel.vesa@nxp.com>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"MyungJoo Ham" <myungjoo.ham@samsung.com>,
	"Kyungmin Park" <kyungmin.park@samsung.com>,
	"Saravana Kannan" <saravanak@google.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Aisheng Dong" <aisheng.dong@nxp.com>,
	"Fabio Estevam" <fabio.estevam@nxp.com>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"Michael Turquette" <mturquette@baylibre.com>,
	"Matthias Kaehlcke" <mka@chromium.org>,
	"Martin Kepplinger" <martink@posteo.de>,
	"Silvano Di Ninno" <silvano.dininno@nxp.com>,
	linux-pm@vger.kernel.org, kernel@pengutronix.de,
	dl-linux-imx <linux-imx@nxp.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-pm-owner@vger.kernel.org
Subject: Re: [PATCH RFC v6 2/9] PM / devfreq: Add generic imx bus scaling driver
Date: Wed, 20 Nov 2019 08:38:47 -0800	[thread overview]
Message-ID: <d1ca09bdeb7580c9b62b491c6eb30148@akkea.ca> (raw)
In-Reply-To: <VI1PR04MB7023E7C380EFA956629EEB67EE4F0@VI1PR04MB7023.eurprd04.prod.outlook.com>

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 ?

Thanks
Angus

> --
> Regards,
> Leonard