From: sumitg <sumitg@nvidia.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: <rjw@rjwysocki.net>, <catalin.marinas@arm.com>, <will@kernel.org>,
<thierry.reding@gmail.com>, <jonathanh@nvidia.com>,
<talho@nvidia.com>, <linux-pm@vger.kernel.org>,
<linux-tegra@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <bbasu@nvidia.com>,
<mperttunen@nvidia.com>
Subject: Re: [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver
Date: Wed, 4 Dec 2019 16:25:57 +0530 [thread overview]
Message-ID: <7347caa6-43a3-f761-de83-481b45f7b22a@nvidia.com> (raw)
In-Reply-To: <20191204054043.o4ff7pnqec3fwdgu@vireshk-i7>
Hi Viresh,
On 04/12/19 11:10 AM, Viresh Kumar wrote:
> Hi Sumit,
>
> On 03-12-19, 23:02, Sumit Gupta wrote:
>> Add support for CPU frequency scaling on Tegra194. The frequency
>> of each core can be adjusted by writing a clock divisor value to
>> an MSR on the core. The range of valid divisors is queried from
>> the BPMP.
>>
>> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
>> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
>> ---
>> drivers/cpufreq/Kconfig.arm | 6 +
>> drivers/cpufreq/Makefile | 1 +
>> drivers/cpufreq/tegra194-cpufreq.c | 423 +++++++++++++++++++++++++++++++++++++
>> 3 files changed, 430 insertions(+)
>> create mode 100644 drivers/cpufreq/tegra194-cpufreq.c
> Overall these are the things that you are doing here in the driver:
>
> - open coded clk_{get|set}_rate(), why can't you implement a clock
> driver for the CPU and use the clk framework? You may not need the
> (hacky) work-queue usage then probably.
In T194, CCPLEX doesn't have access to set clocks and the
clk_{get|set}_rate() functions set clocks by hook to BPMP R5.
CPU freq can be directly set by CCPLEX using MSR(NVFREQ_REQ_EL1).
As DVFS run's on BPMP, another MSR (NVFREQ_FEEDBACK_EL1) is
used to read the counters and calculate "actual" cpu freq at CCPLEX.
So, "cpuinfo_cur_freq" node gives the actual cpu frequency and not
given by node "scaling_cur_freq".
>
> - populating cpufreq table, you can probably add OPPs instead using
> the same mechanism
We are reading available frequencies from BPMP to populate
cpufreq table and not using static opp table.
>
> - And then you can reuse the cpufreq-dt driver for your platform as
> well, as is the case for few other tegra platforms.
>
next prev parent reply other threads:[~2019-12-04 10:56 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 17:32 [TEGRA194_CPUFREQ Patch 1/3] firmware: tegra: adding function to get BPMP data Sumit Gupta
2019-12-03 17:32 ` [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver Sumit Gupta
2019-12-04 5:40 ` Viresh Kumar
2019-12-04 10:55 ` sumitg [this message]
2019-12-04 11:27 ` Viresh Kumar
2019-12-04 13:57 ` Dmitry Osipenko
2019-12-05 2:51 ` Viresh Kumar
2019-12-05 12:55 ` Dmitry Osipenko
2020-03-25 23:59 ` sumitg
2019-12-04 13:59 ` Dmitry Osipenko
2019-12-05 14:15 ` Dmitry Osipenko
2020-03-26 11:50 ` Viresh Kumar
2020-04-04 18:38 ` sumitg
2020-04-06 2:55 ` Viresh Kumar
2020-04-07 18:18 ` sumitg
2020-04-08 5:53 ` Viresh Kumar
2020-04-08 11:24 ` sumitg
2020-04-09 7:44 ` Viresh Kumar
2020-04-09 11:21 ` Sumit Gupta
2020-04-13 6:21 ` Viresh Kumar
2020-04-13 12:20 ` Sumit Gupta
2020-04-14 5:45 ` Viresh Kumar
2020-04-15 11:25 ` Sumit Gupta
2020-04-16 3:37 ` Viresh Kumar
2020-04-16 7:06 ` Sumit Gupta
2019-12-03 17:32 ` [TEGRA194_CPUFREQ Patch 3/3] arm64: defconfig: Enable CONFIG_ARM_TEGRA194_CPUFREQ Sumit Gupta
2019-12-03 17:42 ` [TEGRA194_CPUFREQ Patch 1/3] firmware: tegra: adding function to get BPMP data Thierry Reding
2019-12-04 8:45 ` Mikko Perttunen
2019-12-04 9:17 ` Viresh Kumar
2019-12-04 9:33 ` Thierry Reding
2019-12-04 9:51 ` Viresh Kumar
2020-04-07 10:05 ` Thierry Reding
2020-04-27 7:18 ` Thierry Reding
2020-04-29 8:21 ` Sumit Gupta
2020-05-06 16:58 ` Thierry Reding
2020-05-20 14:43 ` Rob Herring
2020-05-20 15:38 ` Thierry Reding
2020-05-20 16:21 ` Rob Herring
2019-12-04 10:21 ` Mikko Perttunen
2019-12-04 10:26 ` Viresh Kumar
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