linux-kernel - Re: [PATCH] intel_idle: Add RaptorLake support

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Message-ID: <7e2c1da24b48217045e8ad95b739ec96cdce5931.camel@intel.com>
Date:   Sun, 20 Aug 2023 09:20:32 +0000
From:   "Zhang, Rui" <rui.zhang@...el.com>
To:     "smarter3@...il.com" <smarter3@...il.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
        "noltari@...il.com" <noltari@...il.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "Bityutskiy, Artem" <artem.bityutskiy@...el.com>,
        "Kumar, Vinay" <vinay.kumar@...el.com>
Subject: Re: [PATCH] intel_idle: Add RaptorLake support

On Sat, 2023-08-19 at 21:41 +0200, Guillaume Martres wrote:
> On 1/19/23 17:13, Zhang, Rui wrote:
> > On Thu, 2023-01-19 at 08:02 +0100, Álvaro Fernández Rojas wrote:
> > > This patch adds RaptorLake support to the intel_idle driver.
> > > 
> > > Since RaptorLake and AlderLake C-state are characteristics the
> > > same,
> > > we use
> > > AlderLake C-states tables for RaptorLake as well.
> > 
> > RPL and ADL have same cstates and use the same mwait hints, but the
> > latency of each c-state are still different on different platforms.
> > So we can not just duplicate the ADL table on RPL.
> > 
> > There is an effort ongoing that measures the latency of each
> > cstate on the RPL platforms. And based on the measurement result,
> > we
> > can decide if a new custom table is needed or we can just copy the
> > previous platform. Hopefully we will have a patch in a couple of
> > weeks.
> 
> Hi, I just stumbled upon this patch series as I was wondering about
> the
> lack of support for Raptor Lake in intel_idle.

intel_idle support for RaptorLake, and also other platforms that don't
have a custom table, is always there as long as we have BIOS support.
The custom table is just an optimization.

>  Your last message from
> January mentions a future patch, is it available anywhere or is this
> still future work?
> 

This is still work in progress because there are still some open
questions that we cannot answer from our measurement, and the table is
not finalized yet.

thanks,
rui