[ Upstream commit 4c4cdc4c63853fee48c02e25c8605fb65a6c9924 ]
According to the ACPI 6.3 specification, the _PSD method is optional
when using CPPC. The underlying assumption is that each CPU can change
frequency independently from all other CPUs; _PSD is provided to tell
the OS that some processors can NOT do that.
However, the acpi_get_psd() function returns ENODEV if there is no _PSD
method present, or an ACPI error status if an error occurs when evaluating
_PSD, if present. This makes _PSD mandatory when using CPPC, in violation
of the specification, and only on Linux.
This has forced some firmware writers to provide a dummy _PSD, even though
it is irrelevant, but only because Linux requires it; other OSPMs follow
the spec. We really do not want to have OS specific ACPI tables, though.
So, correct acpi_get_psd() so that it does not return an error if there
is no _PSD method present, but does return a failure when the method can
not be executed properly. This allows _PSD to be optional as it should
be.
Signed-off-by: Al Stone <ahs3@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ca1721c5bee77105829cbd7baab8ee0eab85b06d ]
On Apple machines, plugging-in or unplugging the power triggers a GPE
for the EC. Since these machines expose an SBS device, this GPE ends
up triggering the acpi_sbs_callback(). This in turn tries to get the
status of the SBS charger. However, on MBP13,* and MBP14,* machines,
performing the smbus-read operation to get the charger's status triggers
the EC's GPE again. The result is an endless re-triggering and handling
of that GPE, consuming significant CPU resources (> 50% in irq).
In the end this is quite similar to commit 3031cddea633 (ACPI / SBS:
Don't assume the existence of an SBS charger), except that on the above
machines a status of all 1's is returned. And like there, we just want
ignore the charger here.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=198169
Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
