linux-kernel - Re: [PATCH] bus: ti-sysc: Fix gpt12 system timer issue with reserved status

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Date:   Tue, 10 Aug 2021 15:52:15 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     Pavel Machek <pavel@...x.de>
Cc:     sashal@...nel.org, linux-omap@...r.kernel.org,
        Dave Gerlach <d-gerlach@...com>,
        Faiz Abbas <faiz_abbas@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Grygorii Strashko <grygorii.strashko@...com>,
        Keerthy <j-keerthy@...com>, Nishanth Menon <nm@...com>,
        Suman Anna <s-anna@...com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Jarkko Nikula <jarkko.nikula@...mer.com>
Subject: Re: [PATCH] bus: ti-sysc: Fix gpt12 system timer issue with reserved
 status

* Pavel Machek <pavel@...x.de> [210810 12:40]:
> Hi!
> 
> I noticed the issue while reviewing stable kernels, as this is being
> backported.
> 
> > Jarkko Nikula <jarkko.nikula@...mer.com> reported that Beagleboard
> > revision c2 stopped booting. Jarkko bisected the issue down to
> > commit 6cfcd5563b4f ("clocksource/drivers/timer-ti-dm: Fix suspend
> > and resume for am3 and am4").
> > 
> > Let's fix the issue by tagging system timers as reserved rather than
> > ignoring them. And let's not probe any interconnect target module child
> > devices for reserved modules.
> 
> +++ b/drivers/bus/ti-sysc.c
> > @@ -3093,8 +3095,8 @@ static int sysc_probe(struct platform_device *pdev)
> >  		return error;
> >  
> >  	error = sysc_check_active_timer(ddata);
> > -	if (error)
> > -		return error;
> > +	if (error == -EBUSY)
> > +		ddata->reserved = true;
> >  
> >  	error = sysc_get_clocks(ddata);
> >  	if (error)
> 
> What is going on here? First, we silently ignore errors other than
> EBUSY. Second, sysc_check_active_timer() can't return -EBUSY: it
> returns either 0 or -ENXIO. (I checked 5.10-stable, mainline and
> -next-20210806).

Thanks for spotting it, looks like there's now a conflict with commit
65fb73676112 ("bus: ti-sysc: suppress err msg for timers used as
clockevent/source"). It seems we should also check for -ENXIO here
too. And yeah it makes sens to return on other errors for sure.

Regards,

Tony