linux-kernel - Re: [PATCH 7/9] irqchip: add a RISC-V PLIC driver

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Message-ID: <20180802115118.GB21984@lst.de>
Date:   Thu, 2 Aug 2018 13:51:18 +0200
From:   Christoph Hellwig <hch@....de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Christoph Hellwig <hch@....de>, palmer@...ive.com,
        jason@...edaemon.net, marc.zyngier@....com, robh+dt@...nel.org,
        mark.rutland@....com, anup@...infault.org, atish.patra@....com,
        devicetree@...r.kernel.org, aou@...s.berkeley.edu,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        shorne@...il.com
Subject: Re: [PATCH 7/9] irqchip: add a RISC-V PLIC driver

On Thu, Aug 02, 2018 at 12:04:04PM +0200, Thomas Gleixner wrote:
> 
> On Thu, 26 Jul 2018, Christoph Hellwig wrote:
> 
> > This patch adds a driver for the Platform Level Interrupt Controller (PLIC)
> 
> See Documentation/process/submitting-patches.rst and search for 'This patch'

Fixed.

> > +static DEFINE_SPINLOCK(plic_toggle_lock);
> 
> RAW_SPINLOCK please.

Done.

> > +static inline void plic_irq_toggle(struct irq_data *d, int enable)
> > +{
> > +	int cpu;
> > +
> > +	writel(enable, plic_regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
> > +	for_each_present_cpu(cpu)
> > +		plic_toggle(cpu, d->hwirq, enable);
> 
> I suggest to make that:
> 
> 	for_each_cpu(cpu, irq_data_get_affinity_mask(d))
> 		plic_toggle(cpu, d->hwirq, enable);

Done.

> That gives you immediately support for interrupt affinity. And then it's
> trivial to do the actual irq_chip::irq_set_affinity() magic as well.

I'll defer that to an incremental patch (added to my todo list).

> > +static void plic_handle_irq(struct pt_regs *regs)
> > +{
> > +	void __iomem *claim =
> > +		plic_hart_offset(smp_processor_id()) + CONTEXT_CLAIM;
> 
> Either ignore the 80 char thing or just move the assignment into the code
> section please. That line break is horrible to read.

That area has been rewritten anyway as we need a cpuid to context
lookup to cover real SOCs vs just qemu.