On 29-02-16, 09:11, Srinivas Pandruvada wrote:

This depends on ACPI configuration, so not guaranteed to have one cpu
per policy. Since this is not guaranteed, I can't change mode to Read
only on some as after I set the cpufreq_driver->attr, the other call to
init may change the mode before the actual attribute creation.
So safe bet is to implement like boost for all CPUs and fail on read
for some CPUs, where this is not present. If this becomes a problem,
then we can revisit.

Perhaps don't look at it on per-cpu basis, but rather per-policy basis
(as the files are going to be shared).

So, maybe just create the attribute always and return errors by
default. Once ->init() is called and you know if a CPU supports it or
not, toggle some internal flag to allow read/write to those sysfs
files.

-- 
viresh