linux-kernel - Re: [PATCH v1 1/8] ACPI: bus: Fix handling of _OSC errors in acpi_run

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Message-ID: <CAJZ5v0hnyBCv-=nq5XbimupJ5T9DS9f4eCgDEC2SiH1gw3zH-A@mail.gmail.com>
Date: Fri, 19 Dec 2025 21:38:44 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Jonathan Cameron <jonathan.cameron@...wei.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Linux ACPI <linux-acpi@...r.kernel.org>, 
	LKML <linux-kernel@...r.kernel.org>, Linux PCI <linux-pci@...r.kernel.org>, 
	Bjorn Helgaas <helgaas@...nel.org>, 
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, Hans de Goede <hansg@...nel.org>, 
	Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v1 1/8] ACPI: bus: Fix handling of _OSC errors in acpi_run_osc()

On Fri, Dec 19, 2025 at 1:26 PM Jonathan Cameron
<jonathan.cameron@...wei.com> wrote:
>
> On Thu, 18 Dec 2025 21:34:26 +0100
> "Rafael J. Wysocki" <rafael@...nel.org> wrote:
>
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > The handling of _OSC errors in acpi_run_osc() is inconsistent.
>
> I wonder if this would be easier to follow with a brief statement
> of why we threat OSC_CAPABILITIES_MASK_ERROR as an error in the first
> place for non query cases?  It took me a brief think and spec read
> to figure that out, but maybe more coffee needed.

Well, this is a good question and it is not obvious IMV.

The current code treats it as an error, but arguably it is not really an error.

If it is a query, it doesn't even make sense to print a debug message
for it, but if it is not a query, the feature mask in the _OSC return
buffer still represents the feature that the OS is expected to
control.  So print the debug messages, but do not fail in that case.

I'll update the patch.