linux-kernel - Re: [PATCH] bus: omap_l3_smx: identify timeout source before rebooting

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Message-ID: <ZMdrN7IqJsASyifi@tp440p.steeds.sam>
Date:   Mon, 31 Jul 2023 10:05:11 +0200
From:   Sicelo <absicsz@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH] bus: omap_l3_smx: identify timeout source before
 rebooting

Hi,

On Mon, Jul 31, 2023 at 08:29:04AM +0300, Tony Lindgren wrote:
> * Sicelo A. Mhlongo <absicsz@...il.com> [230730 20:23]:
> > Identify and print the error source before rebooting the board due to an l3
> > application timeout error, by delaying the BUG_ON. This is helpful when
> > debugging, e.g. via serial.
> 
> Makes sense to try to show some information, but please see the question
> below.
> 
> > diff --git a/drivers/bus/omap_l3_smx.c b/drivers/bus/omap_l3_smx.c
> > index bb1606f5ce2d..70f4903d5468 100644
> > --- a/drivers/bus/omap_l3_smx.c
> > +++ b/drivers/bus/omap_l3_smx.c
> > @@ -170,11 +170,9 @@ static irqreturn_t omap3_l3_app_irq(int irq, void *_l3)
> >  		status = omap3_l3_readll(l3->rt, L3_SI_FLAG_STATUS_0);
> >  		/*
> >  		 * if we have a timeout error, there's nothing we can
> > -		 * do besides rebooting the board. So let's BUG on any
> > -		 * of such errors and handle the others. timeout error
> > -		 * is severe and not expected to occur.
> > +		 * do besides rebooting the board after identifying the
> > +		 * error source.
> >  		 */
> > -		BUG_ON(status & L3_STATUS_0_TIMEOUT_MASK);
> >  	} else {
> >  		status = omap3_l3_readll(l3->rt, L3_SI_FLAG_STATUS_1);
> >  		/* No timeout error for debug sources */
> > @@ -190,6 +188,12 @@ static irqreturn_t omap3_l3_app_irq(int irq, void *_l3)
> >  		ret |= omap3_l3_block_irq(l3, error, error_addr);
> >  	}
> >  
> > +	/*
> > +	 * BUG on application timeout errors since they are severe and not
> > +	 * expected to occur.
> > +	 */
> > +	BUG_ON(status & L3_STATUS_0_TIMEOUT_MASK);
> 
> Aren't you now checking the bit for both L3_SI_FLAG_STATUS_0 and
> L3_SI_FLAG_STATUS_1 register values? I think it should be only for register
> L3_SI_FLAG_STATUS_0 value?
> 

Ah, you are right. It should be:

    `BUG_ON(!int_type && status & L3_STATUS_0_TIMEOUT_MASK);`

I'll send in a v2.

Thanks
Sicelo