linux-kernel - Re: [PATCH v5 08/13] ACPI: add perf low power callback

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Message-ID: <YfKY4k+ZO9of3Ipd@hirez.programming.kicks-ass.net>
Date:   Thu, 27 Jan 2022 14:06:42 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Stephane Eranian <eranian@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kim.phillips@....com,
        acme@...hat.com, jolsa@...hat.com, songliubraving@...com,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v5 08/13] ACPI: add perf low power callback

On Wed, Jan 26, 2022 at 03:34:49PM -0800, Stephane Eranian wrote:
> This patch add an optional callback needed by some PMU features, e.g., AMD

"This patch" is a documented fail.

> BRS, to give a chance to the perf_events code to change its state before
> going to low power and after coming back.
> 
> The callback is void when the PERF_NEEDS_LOPWR_CB flag is not set.
> This flag must be set in arch specific perf_event.h header whenever needed.
> When not set, there is no impact of the ACPI code.
> 
> Signed-off-by: Stephane Eranian <eranian@...gle.com>
> ---
>  drivers/acpi/acpi_pad.c       | 6 ++++++
>  drivers/acpi/processor_idle.c | 5 +++++
>  include/linux/perf_event.h    | 6 ++++++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
> index f45979aa2d64..a306a07a60b5 100644
> --- a/drivers/acpi/acpi_pad.c
> +++ b/drivers/acpi/acpi_pad.c
> @@ -164,6 +164,9 @@ static int power_saving_thread(void *data)
>  				tsc_marked_unstable = 1;
>  			}
>  			local_irq_disable();
> +
> +			perf_lopwr_cb(true);
> +
>  			tick_broadcast_enable();
>  			tick_broadcast_enter();
>  			stop_critical_timings();
> @@ -172,6 +175,9 @@ static int power_saving_thread(void *data)
>  
>  			start_critical_timings();
>  			tick_broadcast_exit();
> +
> +			perf_lopwr_cb(false);
> +
>  			local_irq_enable();
>  
>  			if (time_before(expire_time, jiffies)) {

You forgot to Cc the maintainers of this stinking pile of poo. Can we
please delete it instead?