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Message-ID: <alpine.DEB.2.20.1706271504521.1798@nanos>
Date: Tue, 27 Jun 2017 15:06:26 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Brian Norris <briannorris@...omium.org>
cc: Heiko Stuebner <heiko@...ech.de>,
Linus Walleij <linus.walleij@...aro.org>,
linux-rockchip@...ts.infradead.org,
Julia Cartwright <julia@...com>,
LKML <linux-kernel@...r.kernel.org>, linux-gpio@...r.kernel.org,
John Keeping <john@...anate.com>, linux-pm@...r.kernel.org,
Doug Anderson <dianders@...omium.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
Tony Lindgren <tony@...mide.com>,
"David.Wu" <david.wu@...k-chips.com>,
'黄涛' <huangtao@...k-chips.com>
Subject: Re: [PATCH for 4.12] Revert "pinctrl: rockchip: avoid hardirq-unsafe
functions in irq_chip"
On Tue, 27 Jun 2017, Thomas Gleixner wrote:
> That aside, looking at the commit which caused this discussion:
>
> 88bb94216f59e pinctrl: rockchip: avoid hardirq-unsafe functions in irq_chip
>
> I assume (the changelog lacks details) that the patch want's to avoid a
> might sleep splat from the irq callbacks caused by the regmap spinlock,
> which gets converted into a sleeping lock on RT. It does this by abusing
> the irq_bus_lock() mechanism, which is wrong to begin with.
>
> The only irq chip function which uses the regmap magic is the
> irq_set_type() callback. Now, I have a hard time to understand (though I'm
> no regmap/pinctrl expert) why that regmap stuff needs to be called in the
> first place. The level and the polarity are programmed via:
>
> writel_relaxed(level, gc->reg_base + GPIO_INTTYPE_LEVEL);
> writel_relaxed(polarity, gc->reg_base + GPIO_INT_POLARITY);
>
> Why needs the regmap machinery to be invoked there? The GPIO is already
> muxed and configured as interrupt, otherwise none of the irq functions
> could be invoked. Hmm?
That said, the commit should be reverted and the issue needs to analyzed
proper. We still need the RCU -> SCRU conversion, but that's a different
problem.
Thanks,
tglx
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