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From: Borislav Petkov <bp@alien8.de>
To: Bjorn Helgaas <helgaas@kernel.org>, "Woods, Brian" <Brian.Woods@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	Clemens Ladisch <clemens@ladisch.de>,
	Jean Delvare <jdelvare@suse.com>,
	Guenter Roeck <linux@roeck-us.net>, Pu Wen <puwen@hygon.cn>,
	Jia Zhang <qianyue.zj@alibaba-inc.com>,
	Takashi Iwai <tiwai@suse.de>, Andy Whitcroft <apw@canonical.com>,
	Colin Ian King <colin.king@canonical.com>,
	Myron Stowe <myron.stowe@redhat.com>,
	Sumeet Pawnikar <sumeet.r.pawnikar@intel.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH 2/4] x86/amd_nb: add support for newer PCI topologies
Date: Wed, 7 Nov 2018 17:07:07 +0100	[thread overview]
Message-ID: <20181107160707.GA14169@zn.tnic> (raw)
In-Reply-To: <20181107133856.GA238955@google.com>

On Wed, Nov 07, 2018 at 07:38:56AM -0600, Bjorn Helgaas wrote:
> Firmware supplies ACPI namespace.  The namespace contains an abstract
> description of the platform, including devices.  Devices are
> identified by PNP IDs, which are analogous to PCI vendor/device IDs,
> except that a device may have several generic "compatible device IDs"
> in addition to an ID unique to the device.  Devices may also contain
> methods (supplied by firmware as part of the namespace), which are
> essentially bytecode that can be executed by the ACPI interpreter in
> the kernel.  Linux drivers claim ACPI devices based on PNP ID and
> operate them using either ACPI methods (which can decouple the driver
> from device specifics) or the usual direct MMIO/IO port/MSR style.
> 
> Here's an outline of how it *could* work:
> 
>   - AMD defines "AMD0001" device ID for the CPU temp sensor
>   - BIOS supplies AMD0001 devices in the ACPI namespace
>   - Each AMD0001 device has a _TMP method (supplied by BIOS and
>     specific to the CPU)
>   - Linux driver claims AMD0001 devices
>   - Driver reads temp sensors by executing _TMP methods (Linux ACPI
>     interpreter runs the bytecode)

Thanks for explaining.

> That way when you release a new platform with different temp sensors,
> you update the BIOS AMD0001 devices and _TMP methods to know about
> them, and the old Linux driver works unchanged.

So I don't know about temp sensors - I'm talking about amd_nb which is
something... well, I explained already what it is in my previous mail so
I won't repeat myself.

Anyway, if there is such a PNP ID device - and I believe I have stumbled
upon some blurb about it in the BKDGs - which says "this device
represents the PCI device IDs of a CPU" and if that can be used to
register amd_nb through it, then sure, I don't see why not.

This way, when new CPU comes out and the same PNP ID device is present,
amd_nb would load, sure.

Maybe Brian knows more on the subject...

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply	other threads:[~2018-11-07 16:07 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-02 18:11 [PATCH 0/4] Update DF/SMN access and k10temp for AMD F17h M30h Woods, Brian
2018-11-02 18:11 ` [PATCH 1/4] k10temp: x86/amd_nb: consolidate shared device IDs Woods, Brian
2018-11-02 18:24   ` Guenter Roeck
2018-11-02 18:11 ` [PATCH 2/4] x86/amd_nb: add support for newer PCI topologies Woods, Brian
2018-11-02 19:59   ` Bjorn Helgaas
2018-11-02 23:29     ` Borislav Petkov
2018-11-05 21:45       ` Bjorn Helgaas
2018-11-05 21:56         ` Borislav Petkov
2018-11-06 21:42           ` Bjorn Helgaas
2018-11-06 22:00             ` Borislav Petkov
2018-11-06 23:20               ` Bjorn Helgaas
2018-11-07  9:18                 ` Borislav Petkov
2018-11-07 13:38                   ` Bjorn Helgaas
2018-11-07 16:07                     ` Borislav Petkov [this message]
2018-11-07 17:10                       ` Bjorn Helgaas
2018-11-07 17:17                         ` Borislav Petkov
2018-11-07 19:50                       ` Woods, Brian
2018-11-07 13:51                   ` Guenter Roeck
2018-11-07 17:16                     ` Bjorn Helgaas
2018-11-07 19:15                 ` Srinivas Pandruvada
2018-11-07 21:31                   ` Bjorn Helgaas
2018-11-07 22:42                     ` Srinivas Pandruvada
2018-11-07 23:14                       ` Bjorn Helgaas
2018-11-07 23:30                         ` Srinivas Pandruvada
2018-11-07 23:44                           ` Srinivas Pandruvada
2018-11-08  1:40                         ` Guenter Roeck
2018-11-08 13:59                           ` Bjorn Helgaas
2018-11-05 19:38   ` Borislav Petkov
2018-11-05 20:33     ` Woods, Brian
2018-11-05 21:42       ` Borislav Petkov
2018-11-05 23:32         ` Woods, Brian
2018-11-06  8:27           ` Borislav Petkov
2018-11-02 18:11 ` [PATCH 3/4] x86/amd_nb: add PCI device IDs for F17h M30h Woods, Brian
2018-11-02 18:11 ` [PATCH 4/4] hwmon: k10temp: add support for AMD F17h M30h CPUs Woods, Brian
2018-11-02 18:26   ` Guenter Roeck
2018-11-05 20:32   ` Borislav Petkov

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