Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Sun, 22 Apr 2018 11:34:06 +0200 | Subject | Re: [PATCH] ACPI / scan: Fix regression related to X-Gene UARTs |
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On Fri, Apr 20, 2018 at 5:29 AM, Mark Salter <msalter@redhat.com> wrote: > Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART > devices") caused a regression with some X-Gene based platforms (Mustang > and M400) with invalid DSDT.
I'm not convinced that making changes to the core ACPI device enumeration code in order to cover up for firmware bugs is the right approach.
> The DSDT makes it appear that the UART > device is also a slave device attached to itself. With the above commit > the UART won't be enumerated by ACPI scan (slave serial devices shouldn't > be). So check for X-Gene UART device and skip slace device check on it. > > Signed-off-by: Mark Salter <msalter@redhat.com> > --- > drivers/acpi/scan.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index cc234e6a6297..1dcdd0122862 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device) > fwnode_property_present(&device->fwnode, "baud"))) > return true; > > + /* > + * Firmware on some arm64 X-Gene platforms will make the UART > + * device appear as both a UART and a slave of that UART. Just > + * bail out here for X-Gene UARTs. > + */ > + if (!strcmp(acpi_device_hid(device), "APMC0D08")) > + return false;
Is the device ID never to be used outside of the broken configurations?
Even if that's the plan, how are you going to guarantee that anyway?
> + > INIT_LIST_HEAD(&resource_list); > acpi_dev_get_resources(device, &resource_list, > acpi_check_serial_bus_slave, > --
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