projects/linux·commit 35d4670a

serdev: Fix detection of UART devices on Apple machines.

35d4670a · Ronald Tschalär <[email protected]> · 2020-02-11 11:47:23 -08:00

On Apple devices the _CRS method returns an empty resource template, and
the resource settings are instead provided by the _DSM method. But
commit 33364d63c75d6182fa369cea80315cf1bb0ee38e (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: <[email protected]> # 5.5
Fixes: 33364d63c75d ("serdev: Add ACPI devices by ResourceSource field")
Signed-off-by: Ronald Tschalär <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Commit
35d4670aaec7206b5ef19c842ca33076bde562e4
Parents
b85c8210

Changes

1 files changed · +10 −0

FileStatusAddDelContent
drivers/tty/serdev/core.cmodified+10−0View file

drivers/tty/serdev/core.c

View file
diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index 42345e7..c5f0d93 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -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;