linux-kernel - Re: [PATCH] mfd: axp20x: Do not sleep in the power off handler

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Message-ID: <Y3IgaSWb46QjljfP@google.com>
Date:   Mon, 14 Nov 2022 11:03:05 +0000
From:   Lee Jones <lee@...nel.org>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc:     Samuel Holland <samuel@...lland.org>, Chen-Yu Tsai <wens@...e.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mfd: axp20x: Do not sleep in the power off handler

On Mon, 07 Nov 2022, Dmitry Osipenko wrote:

> On 11/7/22 12:39, Lee Jones wrote:
> > On Mon, 07 Nov 2022, Dmitry Osipenko wrote:
> > 
> >> On 11/6/22 00:29, Samuel Holland wrote:
> >>> Since commit 856c288b0039 ("ARM: Use do_kernel_power_off()"), the
> >>> function axp20x_power_off() now runs inside a RCU read-side critical
> >>> section, so it is not allowed to call msleep(). Use mdelay() instead.
> >>>
> >>> Fixes: 856c288b0039 ("ARM: Use do_kernel_power_off()")
> >>> Signed-off-by: Samuel Holland <samuel@...lland.org>
> >>> ---
> >>>
> >>>  drivers/mfd/axp20x.c | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
> >>> index 88a212a8168c..880c41fa7021 100644
> >>> --- a/drivers/mfd/axp20x.c
> >>> +++ b/drivers/mfd/axp20x.c
> >>> @@ -842,7 +842,7 @@ static void axp20x_power_off(void)
> >>>  		     AXP20X_OFF);
> >>>  
> >>>  	/* Give capacitors etc. time to drain to avoid kernel panic msg. */
> >>> -	msleep(500);
> >>> +	mdelay(500);
> >>>  }
> >>>  
> >>>  int axp20x_match_device(struct axp20x_dev *axp20x)
> >>
> >> ARM was doing local_irq_disable() on power-off before
> >> do_kernel_power_off() was introduced, so this should've been incorrect
> >> for a couple years at least. If I'm not missing anything.
> > 
> > Is that a review?  Care to provide a tag?
> 
> It's a review and my point was that the "Fixes" tag in this patch
> doesn't look correct. But this is minor comment, otherwise patch looks
> okay. Hope that the relevant I2C controller driver supports atomic
> transfer that are required for power-off to work.
> 
> Reviewed-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>

Thanks.

-- 
Lee Jones [李琼斯]