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

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Message-ID: <alpine.LNX.2.20.13.2012221720290.10565@monopod.intra.ispras.ru>
Date:   Tue, 22 Dec 2020 17:45:27 +0300 (MSK)
From:   Alexander Monakov <amonakov@...ras.ru>
To:     "Deucher, Alexander" <Alexander.Deucher@....com>
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

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.

Alexander