Re: [PATCH v2 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag

[Jeremy Linton]

On 6/17/19 7:34 AM, Valentin Schneider wrote:
> Hi Jeremy,
>
> Few nits below.
>
> Also, I had a look at the other PPTT processor flags that were introduced
> in 6.3, and the only other one being used is ACPI_LEAF_NODE in
> acpi_pptt_leaf_node(). However that one already has a handle on the table
> header, so the check_acpi_cpu_flag() isn't of much help there.
>
> I don't believe the other existing flags will benefit from the helper since
> they are more about describing the PPTT tree, but I think it doesn't hurt
> to keep it around for potential future flags.

That was the thought process.

> On 14/06/2019 23:31, Jeremy Linton wrote:
> [...]
> > @@ -517,6 +517,43 @@ static int find_acpi_cpu_topology_tag(unsigned int cpu, int level, int flag)
> >   	return retval;
> >   }
> >   
> > +/**
> > + * check_acpi_cpu_flag() - Determine if CPU node has a flag set
> > + * @cpu: Kernel logical CPU number
> > + * @rev: The PPTT revision defining the flag
> > + * @flag: The flag itself
> > + *
> > + * Check the node representing a CPU for a given flag.
> > + *
> > + * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found or
> > + *	   the table revision isn't new enough.
> > + * Otherwise returns flag value
> > + */
>
> Nit: strictly speaking we're not returning the flag value but its mask
> applied to the flags field. I don't think anyone will care about getting
> the actual flag value, but it should be made obvious in the doc:

Or I clarify the code to actually do what the comments says. Maybe that 
is what John G was also pointing out too?


> -ENOENT if ...
> 0 if the flag isn't set
> > 0 if it is set.
>
> [...]
> > @@ -581,6 +618,21 @@ int cache_setup_acpi(unsigned int cpu)
> >   	return status;
> >   }
> >   
> > +/**
> > + * acpi_pptt_cpu_is_thread() - Determine if CPU is a thread
> > + * @cpu: Kernel logical CPU number
> > + *
> > + *
>
> Nit: extra newline
>
> > + * Return: 1, a thread
> > + *         0, not a thread
> > + *         -ENOENT ,if the PPTT doesn't exist, the CPU cannot be found or
> > + *         the table revision isn't new enough.
> > + */
> > +int acpi_pptt_cpu_is_thread(unsigned int cpu)
> > +{
> > +	return check_acpi_cpu_flag(cpu, 2, ACPI_PPTT_ACPI_PROCESSOR_IS_THREAD);
> > +}
> > +
> >   /**
> >    * find_acpi_cpu_topology() - Determine a unique topology value for a given CPU
> >    * @cpu: Kernel logical CPU number
> > @@ -641,7 +693,6 @@ int find_acpi_cpu_cache_topology(unsigned int cpu, int level)
> [...]