Hi Dan,
On Fri, 12 Jun 2020 at 18:43, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> On Fri, Jun 12, 2020 at 03:11:33PM +0300, Dan Carpenter wrote:
> > +static int cti_pm_setup(struct cti_drvdata *drvdata)
> > +{
> > + int ret;
> > +
> > + if (drvdata->ctidev.cpu == -1)
> > + return 0;
> > +
> > + if (nr_cti_cpu)
> > + goto done;
> > +
> > + cpus_read_lock();
> ^^^^^^^^^^^^^^^^
> One thing which I do wonder is why we have locking here but not in the
> cti_pm_release() function. That was how the original code was so the
> patch doesn't change anything, but I am curious.
>
Good point - the CTI PM code was modelled on the same code in the ETM
drivers, which show the same pattern.
Perhaps something we need to revisit in both drivers.
Regards
Mike
> > + ret = cpuhp_setup_state_nocalls_cpuslocked(
> > + CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
> > + "arm/coresight_cti:starting",
> > + cti_starting_cpu, cti_dying_cpu);
> > + if (ret) {
> > + cpus_read_unlock();
> > + return ret;
> > + }
> > +
> > + ret = cpu_pm_register_notifier(&cti_cpu_pm_nb);
> > + cpus_read_unlock();
> > + if (ret) {
> > + cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
> > + return ret;
> > + }
> > +
> > +done:
> > + nr_cti_cpu++;
> > + cti_cpu_drvdata[drvdata->ctidev.cpu] = drvdata;
> > +
> > + return 0;
> > +}
> > +
> > /* release PM registrations */
> > static void cti_pm_release(struct cti_drvdata *drvdata)
> > {
> > - if (drvdata->ctidev.cpu >= 0) {
> > - if (--nr_cti_cpu == 0) {
> > - cpu_pm_unregister_notifier(&cti_cpu_pm_nb);
> > + if (drvdata->ctidev.cpu == -1)
> > + return;
> >
> > - cpuhp_remove_state_nocalls(
> > - CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
> > - }
> > - cti_cpu_drvdata[drvdata->ctidev.cpu] = NULL;
> > + cti_cpu_drvdata[drvdata->ctidev.cpu] = drvdata;
> > + if (--nr_cti_cpu == 0) {
> > + cpu_pm_unregister_notifier(&cti_cpu_pm_nb);
> > + cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_CTI_STARTING);
> > }
> > }
>
> regards,
> dan carpenter
>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
