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[CPUFREQ] Disable sysfs ui for p4-clockmod.
p4-clockmod has a long history of abuse. It pretends to be a CPU frequency scaling driver, even though it doesn't actually change the CPU frequency, but instead just modulates the frequency with wait-states. The biggest misconception is that when running at the lower 'frequency' p4-clockmod is saving power. This isn't the case, as workloads running slower take longer to complete, preventing the CPU from entering deep C states. However p4-clockmod does have a purpose. It can prevent overheating. Having it hooked up to the cpufreq interfaces is the wrong way to achieve cooling however. It should instead be hooked up to ACPI. This diff introduces a means for a cpufreq driver to register with the cpufreq core, but not present a sysfs interface. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Dave Jones <davej@redhat.com>
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parent
10db2e5cbd
commit
e088e4c9cd
3 changed files with 36 additions and 19 deletions
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@ -276,6 +276,7 @@ static struct cpufreq_driver p4clockmod_driver = {
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.name = "p4-clockmod",
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.owner = THIS_MODULE,
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.attr = p4clockmod_attr,
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.hide_interface = 1,
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};
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@ -754,6 +754,11 @@ static struct kobj_type ktype_cpufreq = {
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.release = cpufreq_sysfs_release,
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};
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static struct kobj_type ktype_empty_cpufreq = {
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.sysfs_ops = &sysfs_ops,
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.release = cpufreq_sysfs_release,
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};
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/**
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* cpufreq_add_dev - add a CPU device
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@ -876,26 +881,36 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
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memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
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/* prepare interface data */
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ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq, &sys_dev->kobj,
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"cpufreq");
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if (ret)
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goto err_out_driver_exit;
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if (!cpufreq_driver->hide_interface) {
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ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
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&sys_dev->kobj, "cpufreq");
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if (ret)
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goto err_out_driver_exit;
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/* set up files for this cpu device */
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drv_attr = cpufreq_driver->attr;
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while ((drv_attr) && (*drv_attr)) {
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ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
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if (ret)
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goto err_out_driver_exit;
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drv_attr++;
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}
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if (cpufreq_driver->get) {
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ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
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if (ret)
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goto err_out_driver_exit;
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}
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if (cpufreq_driver->target) {
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ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
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/* set up files for this cpu device */
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drv_attr = cpufreq_driver->attr;
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while ((drv_attr) && (*drv_attr)) {
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ret = sysfs_create_file(&policy->kobj,
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&((*drv_attr)->attr));
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if (ret)
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goto err_out_driver_exit;
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drv_attr++;
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}
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if (cpufreq_driver->get) {
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ret = sysfs_create_file(&policy->kobj,
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&cpuinfo_cur_freq.attr);
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if (ret)
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goto err_out_driver_exit;
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}
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if (cpufreq_driver->target) {
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ret = sysfs_create_file(&policy->kobj,
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&scaling_cur_freq.attr);
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if (ret)
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goto err_out_driver_exit;
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}
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} else {
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ret = kobject_init_and_add(&policy->kobj, &ktype_empty_cpufreq,
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&sys_dev->kobj, "cpufreq");
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if (ret)
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goto err_out_driver_exit;
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}
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@ -234,6 +234,7 @@ struct cpufreq_driver {
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int (*suspend) (struct cpufreq_policy *policy, pm_message_t pmsg);
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int (*resume) (struct cpufreq_policy *policy);
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struct freq_attr **attr;
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bool hide_interface;
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};
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/* flags */
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