linux-kernel - Re: [PATCH v2] clocksource: Add node counter timer driver for MIPS/Loongson64

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Message-ID: <87sey3b6de.ffs@tglx>
Date: Mon, 27 May 2024 17:51:25 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Jiaxun Yang <jiaxun.yang@...goat.com>, Huacai Chen
 <chenhuacai@...nel.org>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
 Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org, Jiaxun Yang
 <jiaxun.yang@...goat.com>
Subject: Re: [PATCH v2] clocksource: Add node counter timer driver for
 MIPS/Loongson64

Jiaxun!

On Fri, May 17 2024 at 18:13, Jiaxun Yang wrote:

> +static void __iomem *nodecnt_reg;
> +static u64 (*nodecnt_read_fn)(void);
> +
> +static u64 notrace nodecnt_read_2x32(void)
> +{
> +	unsigned int hi, hi2, lo;
> +
> +	do {
> +		hi = readl_relaxed(nodecnt_reg + 4);
> +		lo = readl_relaxed(nodecnt_reg);
> +		hi2 = readl_relaxed(nodecnt_reg + 4);
> +	} while (hi2 != hi);
> +
> +	return (((u64) hi) << 32) + lo;
> +}
> +
> +static u64 notrace nodecnt_read_64(void)
> +{
> +	return readq_relaxed(nodecnt_reg);
> +}
> +
> +static u64 notrace nodecnt_read_csr(void)
> +{
> +	return csr_readq(LOONGSON_CSR_NODECNT);
> +}
> +
> +static u64 nodecnt_clocksource_read(struct clocksource *cs)
> +{
> +	return nodecnt_read_fn();

What's this indirection for? Why dont you update 

> +static struct clocksource nodecnt_clocksource = {
> +	.name	= "nodecnt",
> +	.read	= nodecnt_clocksource_read,

the read function pointer here and spare the indirection?

Thanks

        tglx