On 11/19/20 1:40 PM, Hector Yuan wrote:

On Thu, 2020-11-19 at 12:41 +0000, Lukasz Luba wrote:

quoted

Hi Hector,

On 10/26/20 8:19 AM, Hector Yuan wrote:

quoted

From: "Hector.Yuan" <redacted>

Add cpufreq HW support.

Signed-off-by: Hector.Yuan <redacted>

[snip]

quoted

+
+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.

quoted

quoted

+
+	/* 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.

quoted

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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