From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Sudeep Holla <sudeep.holla@arm.com>,
Jeffy Chen <jeffy.chen@rock-chips.com>
Cc: linux-kernel@vger.kernel.org,
Brian Norris <briannorris@chromium.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Douglas Anderson <dianders@chromium.org>,
Robin Murphy <robin.murphy@arm.com>,
Heiko Stuebner <heiko@sntech.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH v1] arch_topology: Adjust initial CPU capacities with current freq
Date: Fri, 10 Jan 2020 13:01:24 +0100 [thread overview]
Message-ID: <5475692c-e72b-74c1-bd6e-95278703249b@arm.com> (raw)
In-Reply-To: <20200110113711.GB39451@bogus>
On 10/01/2020 12:37, Sudeep Holla wrote:
> On Thu, Jan 09, 2020 at 03:52:14PM +0800, Jeffy Chen wrote:
>> The CPU freqs are not supposed to change before cpufreq policies
>> properly registered, meaning that they should be used to calculate the
>> initial CPU capacities.
>>
>> Doing this helps choosing the best CPU during early boot, especially
>> for the initramfs decompressing.
>>
>> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
>
> [...]
>
>> @@ -146,10 +153,15 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
>> return false;
>> }
>> }
>> - capacity_scale = max(cpu_capacity, capacity_scale);
>> raw_capacity[cpu] = cpu_capacity;
>> pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
>> cpu_node, raw_capacity[cpu]);
>> +
>> + cpu_clk = of_clk_get(cpu_node, 0);
>> + if (!PTR_ERR_OR_ZERO(cpu_clk))
>> + per_cpu(max_freq, cpu) = clk_get_rate(cpu_clk) / 1000;
>> +
>> + clk_put(cpu_clk);
>
> I don't like to assume DVFS to be supplied only using 'clk'. So NACK!
> We have other non-clk mechanism for CPU DVFS and this needs to simply
> use cpufreq APIs to get frequency value if required.
To support this, it's failing on my Arm64 Juno board.
...
[ 0.084858] CPU1 cpu_clk=-517
[ 0.087961] CPU2 cpu_clk=-517
[ 0.091005] CPU0 cpu_clk=-517
[ 0.094121] CPU3 cpu_clk=-517
[ 0.097248] CPU4 cpu_clk=-517
[ 0.100415] CPU5 cpu_clk=-517
...
Since you're on a big.LITTLE platform, did you specify
'capacity-dmips-mhz' for CPUs to be able to distinguish big and little
CPUs before CPUfreq kicks in?
$ grep capacity-dmips-mhz ./arch/arm64/boot/dts/arm/juno.dts
capacity-dmips-mhz = <1024>;
capacity-dmips-mhz = <1024>;
capacity-dmips-mhz = <578>;
capacity-dmips-mhz = <578>;
capacity-dmips-mhz = <578>;
capacity-dmips-mhz = <578>;
next prev parent reply other threads:[~2020-01-10 12:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 7:52 [PATCH v1] arch_topology: Adjust initial CPU capacities with current freq Jeffy Chen
2020-01-10 11:37 ` Sudeep Holla
2020-01-10 11:54 ` Robin Murphy
2020-01-10 12:01 ` Dietmar Eggemann [this message]
2020-01-10 12:28 ` Robin Murphy
2020-01-11 2:51 ` JeffyChen
2020-01-11 15:12 ` Robin Murphy
2020-01-13 3:59 ` JeffyChen
2020-01-10 14:03 ` kbuild test robot
2020-01-10 14:45 ` kbuild test robot
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