linux-kernel - Re: [PATCH] bus: ti-sysc: Use fsleep() instead of usleep_range() in sysc

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Message-ID: <20230913082711.GH5285@atomide.com>
Date:   Wed, 13 Sep 2023 11:27:11 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     Julien Panis <jpanis@...libre.com>
Cc:     linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
        vigneshr@...com
Subject: Re: [PATCH] bus: ti-sysc: Use fsleep() instead of usleep_range() in
 sysc_reset()

* Tony Lindgren <tony@...mide.com> [230822 09:27]:
> * Julien Panis <jpanis@...libre.com> [230821 14:24]:
> > The am335x-evm started producing boot errors because of subtle timing
> > changes:
> > 
> > Unhandled fault: external abort on non-linefetch (0x1008) at 0xf03c1010
> > ...
> > sysc_reset from sysc_probe+0xf60/0x1514
> > sysc_probe from platform_probe+0x5c/0xbc
> > ...
> > 
> > The fix consists in using the appropriate sleep function in sysc reset.
> > For flexible sleeping, fsleep is recommended. Here, sysc delay parameter
> > can take any value in [0 - 255] us range. As a result, fsleep() should
> > be used, calling udelay() for a sysc delay lower than 10 us.
> > 
> > Signed-off-by: Julien Panis <jpanis@...libre.com>
> > Fixes: e709ed70d122 ("bus: ti-sysc: Fix missing reset delay handling")
> > ---
> > Fix boot errors for am335x-evm in sysc_reset(), by using fsleep() instead
> > of usleep_range() function. Thus, udelay() will be called if the configured
> > sysc delay is lower than 10 us (which is usually the case, since the value
> > set in the device tree is currently 2 us).
> 
> OK, interesting. Yeah I've only ever seen values of 2 us needed here.

Applied into fixes thanks

Tony