linux-kernel - Re: [PATCH v3 1/3] ARM: dts: da850: add cpu node and operating points to DT

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Date:   Fri, 12 Apr 2019 16:56:30 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        Kevin Hilman <khilman@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Lechner <david@...hnology.com>,
        Adam Ford <aford173@...il.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH v3 1/3] ARM: dts: da850: add cpu node and operating points
 to DT

Hi Bartosz,

On 08/04/19 1:29 PM, Bartosz Golaszewski wrote:
> From: David Lechner <david@...hnology.com>
> 
> This adds a cpu node and operating points to the common da850.dtsi file.
> 
> Additionally, a regulator is added to the LEGO EV3 board along with
> some board-specific CPU configuration.
> 
> Regulators need to be hooked up on other boards to get them working.
> 
> Signed-off-by: David Lechner <david@...hnology.com>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>

I remember you mentioning about some problems using OCHI and cpufreq
together. Are those resolved now? CPU PLL on DA850 can affect other
peripheral clock frequencies too. So enabling it should really be a
per-board decision.

No problems with adding OPPs to da850.dtsi, but which of those are
enabled on any board should be after some thorough testing and analysis.

Because of that, I think its also better to split da850.dtsi from board
specific changes in this patch.

> +	opp_table: opp-table {
> +		compatible = "operating-points-v2";
> +
> +		opp_100: opp100-100000000 {
> +			opp-hz = /bits/ 64 <100000000>;
> +			opp-microvolt = <1000000 950000 1050000>;
> +		};
> +
> +		opp_200: opp110-200000000 {
> +			opp-hz = /bits/ 64 <200000000>;
> +			opp-microvolt = <1100000 1050000 1160000>;
> +		};
> +
> +		opp_300: opp120-300000000 {
> +			opp-hz = /bits/ 64 <300000000>;
> +			opp-microvolt = <1200000 1140000 1320000>;
> +		};
> +
> +		/*
> +		 * Original silicon was 300MHz max, so higher frequencies
> +		 * need to be enabled on a per-board basis if the chip is
> +		 * capable.
> +		 */
> +
> +		opp_375: opp120-375000000 {
> +			status = "disabled";
> +			opp-hz = /bits/ 64 <375000000>;
> +			opp-microvolt = <1200000 1140000 1320000>;
> +		};
> +
> +		opp_415: opp130-415000000 {
> +			status = "disabled";
> +			opp-hz = /bits/ 64 <415000000>;
> +			opp-microvolt = <1300000 1250000 1350000>;
> +		};
> +
> +		opp_456: opp130-456000000 {
> +			status = "disabled";
> +			opp-hz = /bits/ 64 <456000000>;
> +			opp-microvolt = <1300000 1250000 1350000>;
> +		};

Here, lets stick to OPPs defined in OMAP-L138 data manual (irrespective
of what existing board code has). Page 93 of
http://www.ti.com/lit/ds/symlink/omap-l138.pdf

Thanks,
Sekhar