Re: [PATCH v3] cpufreq: scmi: Skip SCMI devices that aren't used by the CPUs
From: Cristian Marussi <cristian.marussi@arm.com>
Date: 2025-05-07 11:59:57
Also in:
arm-scmi, linux-pm, lkml
On Mon, Apr 28, 2025 at 07:47:28AM -0700, Mike Tipton wrote:
Currently, all SCMI devices with performance domains attempt to register a cpufreq driver, even if their performance domains aren't used to control the CPUs. The cpufreq framework only supports registering a single driver, so only the first device will succeed. And if that device isn't used for the CPUs, then cpufreq will scale the wrong domains.
Hi, bit of lagging behind, my bad.
quoted hunk ↗ jump to hunk
To avoid this, return early from scmi_cpufreq_probe() if the probing SCMI device isn't referenced by the CPU device phandles. This keeps the existing assumption that all CPUs are controlled by a single SCMI device. Signed-off-by: Mike Tipton <redacted> Reviewed-by: Peng Fan <peng.fan@nxp.com> --- Changes in v3: - Use dev_of_node(dev) instead of dev->of_node. - Sanity check scmi_np. - Pick up Reviewed-by from Peng. - Link to v2: https://lore.kernel.org/all/20250421195206.3736128-1-quic_mdtipton@quicinc.com/ (local) Changes in v2: - Return -ENODEV instead of 0 for irrelevant devices. - Link to v1: https://lore.kernel.org/all/20250411212941.1275572-1-quic_mdtipton@quicinc.com/ (local) drivers/cpufreq/scmi-cpufreq.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-)diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c index 944e899eb1be..b63992de9fc7 100644 --- a/drivers/cpufreq/scmi-cpufreq.c +++ b/drivers/cpufreq/scmi-cpufreq.c@@ -393,6 +393,35 @@ static struct cpufreq_driver scmi_cpufreq_driver = { .set_boost = cpufreq_boost_set_sw, }; +static bool scmi_dev_used_by_cpus(struct device *scmi_dev) +{ + struct device_node *scmi_np = dev_of_node(scmi_dev); + struct device_node *np; + struct device *cpu_dev; + int cpu, idx; + + if (!scmi_np) + return false; + + for_each_possible_cpu(cpu) { + cpu_dev = get_cpu_device(cpu); + if (!cpu_dev) + continue; + + np = dev_of_node(cpu_dev); + + if (of_parse_phandle(np, "clocks", 0) == scmi_np)
Shouldn't this, on Success, be released by an of_node_put() (or, BETTER, by some OF-related cleanup.h magic...)
+ return true; + + idx = of_property_match_string(np, "power-domain-names", "perf"); + + if (of_parse_phandle(np, "power-domains", idx) == scmi_np)
Same.
quoted hunk ↗ jump to hunk
+ return true; + } + + return false; +} + static int scmi_cpufreq_probe(struct scmi_device *sdev) { int ret;@@ -401,7 +430,7 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev) handle = sdev->handle; - if (!handle) + if (!handle || !scmi_dev_used_by_cpus(dev)) return -ENODEV; scmi_cpufreq_driver.driver_data = sdev;
Other than the above glitches, LGTM. (I gave it a go on JUNO and some emulated setup..) Reviewed-by: Cristian Marussi <cristian.marussi@arm.com> Tested-by: Cristian Marussi <cristian.marussi@arm.com> Thanks, Cristian