Re: [PATCH] arm_mpam: avoid hour-long timeout on invalid ACPI table entry

[Gavin Shan]

On 11/2/26 9:27 PM, Andre Przywara wrote:
> The ACPI PCCT table contains a "nominal latency" field for the expected
> maximum time it takes to handle a command in the PCC mailbox.
> The generic ACPI code reads this value, but leaves the handling to the
> protocol users.
>
> For MPAM-Fb based MSC signalling, we use a value derived from that number
> as the mailbox timeout. However if the ACPI table leaves this entry at 0,
> the mailbox timeout code interprets this as "forever", and waits for one
> hour.
>
> Avoid that lengthy timeout and just add one microsecond to the read value,
> to come up with a non-zero result in any case.
>
> Found by Sashiko.
>
> Fixes: cb351e3f304b ("arm_mpam: detect and enable MPAM-Fb PCC support")
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>   drivers/resctrl/mpam_devices.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>