Re: [PATCH v4 08/14] clocksource: mips-gic-timer: Enable counter when CPUs start

[Philippe Mathieu-Daudé]

On 11/5/24 12:43, Aleksandar Rikalo wrote:
> From: Paul Burton <paulburton@xxxxxxxxxx>
>
> In multi-cluster MIPS I6500 systems we have a GIC in each cluster, each
> with its own counter. When a cluster powers up the counter will be
> stopped, with the COUNTSTOP bit set in the GIC_CONFIG register.
>
> In single cluster systems it has been fine for us to clear COUNTSTOP
> once in gic_clocksource_of_init() in order to start the counter, since
> with only one cluster we know that we won't be resetting that cluster's
> GIC at any point (ignoring suspend/resume cycles which would need to
> handle clearing COUNTSTOP in the resume path). Once we support
> multi-cluster systems this will only have started the counter in the
> boot cluster, and any CPUs in other clusters will find their counter
> stopped which will break the GIC clock_event_device.
>
> Resolve this by having CPUs clear the COUNTSTOP bit when they come
> online, using the existing gic_starting_cpu() CPU hotplug callback. This
> will allow CPUs in secondary clusters to ensure that the cluster's GIC
> counter is running as expected.
>
> Signed-off-by: Paul Burton <paulburton@xxxxxxxxxx>
> Signed-off-by: Chao-ying Fu <cfu@xxxxxxxxxxxx>
> Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@xxxxxxxxxx>
> Signed-off-by: Aleksandar Rikalo <aleksandar.rikalo@xxxxxxxxxx>
> ---
>   drivers/clocksource/mips-gic-timer.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>