linux-kernel - Re: [PATCH 6.6 1/1] PM: sleep: Restore asynchronous device resume optimization

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Message-ID: <2024090420-protozoan-clench-cca7@gregkh>
Date: Wed, 4 Sep 2024 16:19:36 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Yenchia Chen <yenchia.chen@...iatek.com>
Cc: stable@...r.kernel.org,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 6.6 1/1] PM: sleep: Restore asynchronous device resume
 optimization

On Mon, Sep 02, 2024 at 05:32:48PM +0800, Yenchia Chen wrote:
> From: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> 
> commit 3e999770ac1c7c31a70685dd5b88e89473509e9c upstream.
> 
> Before commit 7839d0078e0d ("PM: sleep: Fix possible deadlocks in core
> system-wide PM code"), the resume of devices that were allowed to resume
> asynchronously was scheduled before starting the resume of the other
> devices, so the former did not have to wait for the latter unless
> functional dependencies were present.
> 
> Commit 7839d0078e0d removed that optimization in order to address a
> correctness issue, but it can be restored with the help of a new device
> power management flag, so do that now.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>
> Signed-off-by: Yenchia Chen <yenchia.chen@...iatek.com>
> ---
>  drivers/base/power/main.c | 117 +++++++++++++++++++++-----------------
>  include/linux/pm.h        |   1 +
>  2 files changed, 65 insertions(+), 53 deletions(-)

Why does this need to be backported?  What bug is it fixing?

confused,

greg k-h