On 12/8/20 7:26 AM, Viresh Kumar wrote:
> On 08-12-20, 07:22, Nicola Mazzucato wrote:
>> On 12/8/20 5:50 AM, Viresh Kumar wrote:
>>> On 02-12-20, 17:23, Nicola Mazzucato wrote:
>>>> nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
>>>> if (nr_opp <= 0) {
>>>> - dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
>>>> - ret = -EPROBE_DEFER;
>>>> - goto out_free_opp;
>>>> + ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
>>>> + if (ret) {
>>>> + dev_warn(cpu_dev, "failed to add opps to the device\n");
>>>> + goto out_free_cpumask;
>>>> + }
>>>> +
>>>> + ret = dev_pm_opp_set_sharing_cpus(cpu_dev, opp_shared_cpus);
>>>> + if (ret) {
>>>> + dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
>>>> + __func__, ret);
>>>> + goto out_free_cpumask;
>>>> + }
>>>> +
>>>
>>> Why do we need to call above two after calling
>>> dev_pm_opp_get_opp_count() ?
>>
>> Sorry, I am not sure to understand your question here. If there are no opps for
>> a device we want to add them to it
>
> Earlier we used to call handle->perf_ops->device_opps_add() and
> dev_pm_opp_set_sharing_cpus() before calling dev_pm_opp_get_opp_count(), why is
> the order changed now ?
True. The order has changed to take into account the fact that when we have
per-cpu + opp-shared, we don't need to add opps for devices which already have them.
>
>> otherwise no need as they would be duplicated.
>
> I am not sure why they would be duplicated in your case. I though
> device_opps_add() is responsible for dynamically adding the OPPs here.
In case of per-cpu + opp-shared, with the "previous order" we would try to add
opps to a device which already has them, in fact attempting to add duplicates.
Nothing wrong with it, but a lot of warnings are thrown.
>
>>> And we don't check the return value of
>>> the below call anymore, moreover we have to call it twice now.
>>
>> This second get_opp_count is required such that we register em with the correct
>> opp number after having added them. Without this the opp_count would not be correct.
>
> What if the count is still 0 ? What about deferred probe we were doing earlier ?
My assumption is to rely on the two above to fail if there was something wrong.
For the deferred probe, I am not sure it is still a useful case to have, but I
will let Sudeep have his view also on this.
>
Thanks Viresh, hope it's a bit more clear now.
Nicola
