linux-kernel - RE: amd-pmc s2idle driver issues

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Date:   Tue, 22 Dec 2020 15:20:15 +0000
From:   "Deucher, Alexander" <Alexander.Deucher@....com>
To:     Alexander Monakov <amonakov@...ras.ru>
CC:     "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "S-k, Shyam-sundar" <Shyam-sundar.S-k@....com>,
        Hans de Goede <hdegoede@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: amd-pmc s2idle driver issues

[AMD Public Use]

> -----Original Message-----
> From: Alexander Monakov <amonakov@...ras.ru>
> Sent: Tuesday, December 22, 2020 9:45 AM
> To: Deucher, Alexander <Alexander.Deucher@....com>
> Cc: platform-driver-x86@...r.kernel.org; S-k, Shyam-sundar <Shyam-
> sundar.S-k@....com>; Hans de Goede <hdegoede@...hat.com>; linux-
> kernel@...r.kernel.org
> Subject: RE: amd-pmc s2idle driver issues
> 
> On Tue, 22 Dec 2020, Deucher, Alexander wrote:
> 
> > > I've tried the "platform/x86: amd-pmc: Add AMD platform support for
> > > S2Idle"
> > > patch on my Acer Swift SF314-42 laptop (Renoir SoC, Ryzen 4500U CPU)
> > > and hit the following issues:
> > >
> > > 1. The driver doesn't bind to any device. It has the following binding table:
> > >
> > > +static const struct acpi_device_id amd_pmc_acpi_ids[] = {
> > > +	{"AMDI0005", 0},
> > > +	{"AMD0004", 0},
> > > +	{ }
> > > +};
> > >
> > > This laptop has "AMD0005" instead. Adding it to the list allows the
> > > driver to successfully probe.
> > >
> > > 2. The debugfs interface does not seem to be very helpful. It shows
> > >
> > > SMU FW Info: ffffffff
> > >
> > > It's not very informative. The code seems to be fetching SMU version
> > > from mmio, so I guess the file should be saying "FW version" rather
> > > than "FW Info", and then, I think version number is not supposed to be "-
> 1".
> > >
> >
> > Does your platform support modern standby?  You may have to select
> > between legacy S3 and modern standby in the sbios.
> 
> Yes. Out-of-the-box it's a "modern standby" laptop. There's a "hidden"
> bios menu with extra settings that apparently allows to select legacy S3.
> I did not change it, so I'm testing the "modern" mode.
> 
> Note that this driver fetches SMU version from MMIO, which looks odd to
> me:
> elsewhere (i.e. in the amdgpu driver) SMU version is retrieved by issuing the
> corresponding SMU command, as far as I can tell.

There are multiple interfaces to the SMU. It's shared by the entire SoC on APUs.

Alex