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Hans de Goede 2d42aacea8 ACPI: x86: Add PNP_UART1_SKIP quirk for Lenovo Blade2 tablets
[ Upstream commit d8f20383a2 ]

The x86 Android tablets on which quirks to skip looking for a matching
UartSerialBus resource and instead unconditionally create a serial bus
device (serdev) are necessary there are 2 sorts of serialports:

ACPI enumerated highspeed designware UARTs, these are the ones which
typcially need to be skipped since they need a serdev for the attached
BT HCI.

A PNP enumerated UART which is part of the PCU. So far the existing
quirks have ignored this. But on the Lenovo Yoga Tablet 2 Pro 1380
models this is used for a custom fastcharging protocol. There is
a Micro USB switch which can switch the USB data lines to this uart
and then a 600 baud protocol is used to configure the charger for
a voltage higher then 5V.

Add a new ACPI_QUIRK_PNP_UART1_SKIP quirk type and set this for
the existing entry for the Lenovo Yoga Tablet 2 830 / 1050 models.
Note this will lead to unnecessarily also creating a serdev for
the PCU UART on the 830 / 1050 which don't need this, but the UART
is not used otherwise there so that is not a problem.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-06-27 13:49:01 +02:00
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