Re: [PATCH v5 2/5] firmware: tegra: bpmp: Add ACPI support

[Sudeep Holla]

On Fri, Nov 06, 2026 at 01:18:56PM +0100, Thierry Reding wrote:
> On Fri, Nov 06, 2026 at 09:25:56AM +0000, Sudeep Holla wrote:

[...]

> > 
> > I am bit concerned as MBWT is something to do with memory bandwidth
> > throttling and resctrl provides user ABI for such things, this sysfs
> > may be duplicating part of it.
> > 
> > > The sysfs knobs exposed in patches 4 and 5 exist because the bandwidth
> > > caps may need to be adjusted dynamically at runtime. It is indeed a bit
> > > absurd to bootstrap a restricted version of BPMP like this for just this
> > > one feature, but I don't see any alternatives.
> > > 
> > 
> > Is MPAM/resctrl path explored and you have valid reasons to not use that
> > and create your own sysfs ?
> 
> My understanding is that only monitoring is implemented for MPAM with no
> way of actually controlling bandwidth through it.
> 

For once I did get that doubt as I don't have much knowledge on MPAM or
resctrl in the kernel. So before replying to you, I had a look at
Section "Memory bandwidth Allocation and monitoring" in
Documentation/filesystems/resctrl.rst which made me understand it as
supported. I may be wrong, but it sounds out to have controls and monitors
in different places in general.

> I've started an internal discussion to evaluate whether we can avoid
> custom sysfs attributes in favour of exposing them through resctrl.
> 

Thanks.

-- 
Regards,
Sudeep