Commit 35d4670a authored Feb 11, 2020 by Ronald Tschalär Committed by Greg Kroah-Hartman Mar 06, 2020

serdev: Fix detection of UART devices on Apple machines.

On Apple devices the _CRS method returns an empty resource template, and
the resource settings are instead provided by the _DSM method. But
commit 33364d63 (serdev: Add ACPI
devices by ResourceSource field) changed the search for serdev devices
to require valid, non-empty resource template, thereby breaking Apple
devices and causing bluetooth devices to not be found.

This expands the check so that if we don't find a valid template, and
we're on an Apple machine, then just check for the device being an
immediate child of the controller and having a "baud" property.

Cc: <stable@vger.kernel.org> # 5.5
Fixes: 33364d63 ("serdev: Add ACPI devices by ResourceSource field")
Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
Link: https://lore.kernel.org/r/20200211194723.486217-1-ronald@innovation.ch

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b85c8210

drivers/tty/serdev/core.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@
		#include <linux/sched.h>
		#include <linux/serdev.h>
		#include <linux/slab.h>
		#include <linux/platform_data/x86/apple.h>

		static bool is_registered;
		static DEFINE_IDA(ctrl_ida);
		@@ -631,6 +632,15 @@ static int acpi_serdev_check_resources(struct serdev_controller *ctrl,
		if (ret)
		return ret;

		/*
		* Apple machines provide an empty resource template, so on those
		* machines just look for immediate children with a "baud" property
		* (from the _DSM method) instead.
		*/
		if (!lookup.controller_handle && x86_apple_machine &&
		!acpi_dev_get_property(adev, "baud", ACPI_TYPE_BUFFER, NULL))
		acpi_get_parent(adev->handle, &lookup.controller_handle);

		/* Make sure controller and ResourceSource handle match */
		if (ACPI_HANDLE(ctrl->dev.parent) != lookup.controller_handle)
		return -ENODEV;

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