Re: [PATCH for 4.12] Revert "pinctrl: rockchip: avoid hardirq-unsafe functions in irq_chip"

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

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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