From: linux-acpi-owner(a)vger.kernel.org [mailto:linux-acpi-
owner(a)vger.kernel.org] On Behalf Of Bjorn Helgaas
Sent: Thursday, January 18, 2018 11:11 AM
To: Hans de Goede <hdegoede(a)redhat.com>
Cc: Rafael J . Wysocki <rjw(a)rjwysocki.net>; Len Brown <lenb(a)kernel.org>;
Bjorn Helgaas <bhelgaas(a)google.com>; Moore, Robert
<robert.moore(a)intel.com>; Zheng, Lv <lv.zheng(a)intel.com>; linux-
acpi(a)vger.kernel.org; linux-pci(a)vger.kernel.org; devel(a)acpica.org
Subject: Re: ACPI: Do not call _STA on battery devices with unmet dependencies
On Thu, Jan 18, 2018 at 05:03:55PM +0100, Hans de Goede wrote:
> Hi All,
> The ACPI code already contains quite a bit of code to not bind the
> ACPI-battery until all deps for an ACPI battery device have been met,
> but on some devices calling _STA before all deps are met is a problem
> too because the _STA method uses an i2c OpRegion there.
Could you explain why _STA method using an I2C OpRegion is problematic?
> Here is the DSDT of the device I'm seeing this on:
This looks like interesting info, but (a) this link isn't mentioned in the actual
patches, and (b) it's conceivable that fedorapeople.org
could go away someday.
If this were a PCI series, I would suggest opening a report at bugzilla.kernel.org
attaching the DSL there, and including the link in the patch changelog.
> This series modifies the kernel to not call _STA until all deps are
> met, mirroring the binding behavior of the battery driver.
> Without this series a total of 32 ACPI errors get printend to the
> console on boot, there are 4 errors per _STA call, 2 battery devices
> on this system and 4 _STA calls per battery device.
> The first commit is a preparation commit for making the ACPICA changes
> in the 4th commit, this commit is necessary to not break things after
> the ACPICA changes.
> The second commit modifies acpi_bus_get_status to not call _STA on
> battery devices until all deps are met. This fixes 2 of the 4 too
> early _STA calls triggering these errors.
> The third commit makes the device instantiation code use
> acpi_bus_get_status instead of acpi_bus_get_status_handle so that the
> code to get the initial status also does not makes 1 too early _STA call.
> The fourth commit changes the ACPICA acpi_get_object_info function to
> not call _STA. Only 1 user (which is fixed in the first commit) cares
> about acpi_device_info.current_status. And the ACPICA code has this
> * Note: This interface is intended to be used during the initial
> * discovery namespace traversal. Therefore, no complex methods can be
> * executed, especially those that access operation regions.
> Therefore, do
> * not add any additional methods that could cause problems in this area.
> * Because of this reason support for the following methods has been
> * this was the fate of the _SUB method which was found to cause such
> * problems and was removed (11/2015).
> The described problems with the _SUB method clearly also apply to the
> _STA method, so removing it from acpi_get_object_info seems like it is
> the right thing to do here. This too fixes 1 too early _STA call, so
> that with all
> 4 patches in place we've fixed all 4 too early _STA calls.
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