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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2024-02-26 17:45:11 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2024-02-27 17:54:59 +0100
commit520c2286c222c0a6c9b366e9c2a6c42c3fc091ed (patch)
treefa87360e8a25893ee9ea11f2bd20c603db3d26f3 /scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h
parent1b4f02a34f095b96de36fa16755f5598ba380939 (diff)
ACPI: scan: Rework Device Check and Bus Check notification handling
The underlying problem is the handling of the enabled bit in device status (bit 1 of _STA return value) which is required by the ACPI specification to be observed in addition to the present bit (bit 0 of _STA return value) [1], but Linux does not observe it. Since Linux has not looked at that bit for a long time, it is generally risky to start obseving it in all device enumeration cases, especially at the system initialization time, but it can be observed when the kernel receives a Bus Check or Device Check notification indicating a change in device configuration. In those cases, seeing the enabled bit clear may be regarded as an indication that the device at hand should not be used any more. For this reason, rework the handling of Device Check and Bus Check notifications in the ACPI core device enumeration code in the following way: 1. Rename acpi_bus_trim_one() to acpi_scan_check_and_detach() and make it check device status if its second argument is not NULL, in which case it will detach scan handlers or ACPI drivers from devices whose _STA returns the enabled bit clear. 2. Make acpi_scan_device_check() and acpi_scan_bus_check() invoke acpi_scan_check_and_detach() with a non-NULL second argument unconditionally, so scan handlers and ACPI drivers are detached from the target device and its ancestors if their _STA returns the enabled bit clear. Link: https://uefi.org/specs/ACPI/6.5/06_Device_Configuration.html#sta-device-status # [1] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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