Re: [PATCH 4.4 28/74] ACPI / scan: Prefer devices without _HID/_CID for _ADR matching

From: Jiri Slaby
Date: Thu Feb 01 2018 - 03:46:48 EST


On 01/29/2018, 01:56 PM, Greg Kroah-Hartman wrote:
> 4.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> commit c2a6bbaf0c5f90463a7011a295bbdb7e33c80b51 upstream.
>
> The way acpi_find_child_device() works currently is that, if there
> are two (or more) devices with the same _ADR value in the same
> namespace scope (which is not specifically allowed by the spec and
> the OS behavior in that case is not defined), the first one of them
> found to be present (with the help of _STA) will be returned.
>
> This covers the majority of cases, but is not sufficient if some of
> the devices in question have a _HID (or _CID) returning some valid
> ACPI/PNP device IDs (which is disallowed by the spec) and the
> ASL writers' expectation appears to be that the OS will match
> devices without a valid ACPI/PNP device ID against a given bus
> address first.
>
> To cover this special case as well, modify find_child_checks()
> to prefer devices without ACPI/PNP device IDs over devices that
> have them.
>
> Suggested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>

You seem you took this from SLE12-SP2? But where did you take the
upstream commit SHA from? In SLE, I have "Git-commit: fdad4e7a876a2..."
which is the correct SHA of this patch. The above c2a6bbaf0c is a
different patch. So are your scripts broken or is this a manual oversight?

> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> ---
> drivers/acpi/glue.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> --- a/drivers/acpi/glue.c
> +++ b/drivers/acpi/glue.c
> @@ -99,13 +99,13 @@ static int find_child_checks(struct acpi
> return -ENODEV;
>
> /*
> - * If the device has a _HID (or _CID) returning a valid ACPI/PNP
> - * device ID, it is better to make it look less attractive here, so that
> - * the other device with the same _ADR value (that may not have a valid
> - * device ID) can be matched going forward. [This means a second spec
> - * violation in a row, so whatever we do here is best effort anyway.]
> + * If the device has a _HID returning a valid ACPI/PNP device ID, it is
> + * better to make it look less attractive here, so that the other device
> + * with the same _ADR value (that may not have a valid device ID) can be
> + * matched going forward. [This means a second spec violation in a row,
> + * so whatever we do here is best effort anyway.]
> */
> - return sta_present && list_empty(&adev->pnp.ids) ?
> + return sta_present && !adev->pnp.type.platform_id ?
> FIND_CHILD_MAX_SCORE : FIND_CHILD_MIN_SCORE;
> }
>
>
>


--
js
suse labs