Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw setting

[Rafael J. Wysocki]

On 5/18/2020 9:41 AM, Viresh Kumar wrote:
> On 16-05-20, 15:52, Serge Semin wrote:
> > On Fri, May 15, 2020 at 05:58:47PM +0200, Rafael J. Wysocki wrote:
> > > > @@ -2554,7 +2554,7 @@ static int cpufreq_boost_set_sw(int state)
> > > >    			break;
> > > >    	}
> > > > -	return ret;
> > > > +	return ret < 0 ? ret : 0;
> > > >    }
> > > >    int cpufreq_boost_trigger_state(int state)
> > > IMO it is better to update the caller of this function to handle the
> > > positive value possibly returned by it correctly.
> > Could you elaborate why? Viresh seems to be ok with this solution.
> And it is absolutely fine for Rafael to not agree with it :)
>
> > As I see it the caller doesn't expect the positive value returned by the
> > original freq_qos_update_request(). It just doesn't need to know whether the
> > effective policy has been updated or not, it only needs to make sure the
> > operations has been successful. Moreover the positive value is related only
> > to the !last! active policy, which doesn't give the caller a full picture
> > of the policy change anyway. So taking all of these into account I'd leave the
> > fix as is.
> Rafael: This function is called via a function pointer, which can call
> this or a platform dependent routine (like in acpi-cpufreq.c), and it
> would be reasonable IMO for the return of that callback to only look
> for 0 or negative values, as is generally done in the kernel.

But it only has one caller that can easily check ret < 0 instead of just 
ret, so the extra branch can be saved.

That said if you really only want it to return 0 on success, you may as 
well add a ret = 0; statement (with a comment explaining why it is 
needed) after the last break in the loop.

Cheers!