linux-kernel - Re: [PATCH] pwm: berlin: Fix wrong register in suspend/resume

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Message-ID: <jioslz4fxpjhmrbjpvihorkuc5w6uof64zhmoeogil4lkjpz2m@xdqn734ie57v>
Date: Tue, 19 Aug 2025 08:15:52 +0200
From: Uwe Kleine-König <ukleinek@...nel.org>
To: Jisheng Zhang <jszhang@...nel.org>
Cc: linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pwm: berlin: Fix wrong register in suspend/resume

Hello,

On Mon, Aug 18, 2025 at 08:09:33PM +0800, Jisheng Zhang wrote:
> On Sun, Aug 17, 2025 at 12:52:01PM +0200, Uwe Kleine-König wrote:
> > On Fri, Aug 15, 2025 at 11:10:16AM +0800, Jisheng Zhang wrote:
> > > diff --git a/drivers/pwm/pwm-berlin.c b/drivers/pwm/pwm-berlin.c
> > > index 831aed228caf..858d36991374 100644
> > > --- a/drivers/pwm/pwm-berlin.c
> > > +++ b/drivers/pwm/pwm-berlin.c
> > > @@ -234,7 +234,7 @@ static int berlin_pwm_suspend(struct device *dev)
> > >  	for (i = 0; i < chip->npwm; i++) {
> > >  		struct berlin_pwm_channel *channel = &bpc->channel[i];
> > >  
> > > -		channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE);
> > > +		channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_EN);
> > 
> > BERLIN_PWM_ENABLE is 1 and BERLIN_PWM_EN is 0. What is the effect? Is
> > the low bit just ignored and the right thing happens? Or does this
> 
> operate the wrong address then kernel panic
> 
> > result in a bus exception and the machine catches fire?
> 
> Yep, cpu exception then kernel panic.

Can you please mention that in the commit log to make reader able to
judge the importance, please?

> > If it's more the latter than the former, I wonder how that didn't pop up
> > earlier.
> 
> This bug has been fixed in vendor's repo for a long time, it's just
> because we didn't upstream the fix.

Wow.

Best regards
Uwe

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