Messages in this thread | | | Subject | Re: [PATCH v8 1/3] cpufreq: mediatek-hw: Add support for CPUFREQ HW | From | Lukasz Luba <> | Date | Thu, 19 Nov 2020 15:14:03 +0000 |
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On 11/19/20 1:40 PM, Hector Yuan wrote: > On Thu, 2020-11-19 at 12:41 +0000, Lukasz Luba wrote: >> Hi Hector, >> >> On 10/26/20 8:19 AM, Hector Yuan wrote: >>> From: "Hector.Yuan" <hector.yuan@mediatek.com> >>> >>> Add cpufreq HW support. >>> >>> Signed-off-by: Hector.Yuan <hector.yuan@mediatek.com> >> >> [snip] >> >>> + >>> +static int mtk_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) >>> +{ >>> + struct cpufreq_mtk *c; >>> + struct device *cpu_dev; >>> + struct em_data_callback em_cb = EM_DATA_CB(mtk_cpufreq_get_cpu_power); >>> + struct pm_qos_request *qos_request; >>> + int sig, pwr_hw = CPUFREQ_HW_STATUS | SVS_HW_STATUS; >>> + >>> + qos_request = kzalloc(sizeof(*qos_request), GFP_KERNEL); >>> + if (!qos_request) >>> + return -ENOMEM; >>> + >>> + cpu_dev = get_cpu_device(policy->cpu); >>> + if (!cpu_dev) { >>> + pr_err("failed to get cpu%d device\n", policy->cpu); >>> + return -ENODEV; >>> + } >>> + >>> + c = mtk_freq_domain_map[policy->cpu]; >>> + if (!c) { >>> + pr_err("No scaling support for CPU%d\n", policy->cpu); >>> + return -ENODEV; >>> + } >>> + >>> + cpumask_copy(policy->cpus, &c->related_cpus); >>> + >>> + policy->freq_table = c->table; >>> + policy->driver_data = c; >> >> To control frequency transition rate in schedutil, you might >> be interested in setting: >> >> policy->cpuinfo.transition_latency = <mtk_value_here>; >> >> Example, when this latency value comes from FW [1] >> > OK, I will add it in v9. >>> + >>> + /* Let CPUs leave idle-off state for SVS CPU initializing */ >>> + cpu_latency_qos_add_request(qos_request, 0); >>> + >>> + /* HW should be in enabled state to proceed now */ >>> + writel_relaxed(0x1, c->reg_bases[REG_FREQ_ENABLE]); >>> + >>> + if (readl_poll_timeout(c->reg_bases[REG_FREQ_HW_STATE], sig, >>> + (sig & pwr_hw) == pwr_hw, POLL_USEC, >>> + TIMEOUT_USEC)) { >>> + if (!(sig & CPUFREQ_HW_STATUS)) { >>> + pr_info("cpufreq hardware of CPU%d is not enabled\n", >>> + policy->cpu); >>> + return -ENODEV; >>> + } >>> + >>> + pr_info("SVS of CPU%d is not enabled\n", policy->cpu); >>> + } >>> + >>> + em_dev_register_perf_domain(cpu_dev, c->nr_opp, &em_cb, policy->cpus); >> >> Please keep in mind that this is going to be changed soon with a new >> argument: 'milliwatts'. It's queued in pm/linux-next [2]. >> > OK, thanks for the remind. >> Regards, >> Lukasz >> >> [1] >> https://elixir.bootlin.com/linux/latest/source/drivers/cpufreq/scmi-cpufreq.c#L194 >> [2] >> https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=c250d50fe2ce627ca9805d9c8ac11cbbf922a4a6 >> >
Also, based on function mtk_cpufreq_hw_target_index(), which looks really simple, you might consider to have fast_switch enabled.
It will allow SchedUtil governor to change frequency directly and not create a dedicated deadline thread for it. It pays off.
You have to experiment with something like:
policy->fast_switch_possible = true;
static struct cpufreq_driver cpufreq_mtk_hw_driver = { ... .fast_switch = mtk_cpufreq_hw_fast_switch ... }
Again, scmi-cpufreq.c would be a good pattern to follow.
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