linux-kernel - Re: [PATCH v8 1/2] clocksource: loongson2

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Date:   Thu, 3 Nov 2022 08:14:35 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     zhuyinbo@...ngson.cn
Cc:     chenhuacai@...nel.org, daniel.lezcano@...aro.org,
        devicetree@...r.kernel.org, jiaxun.yang@...goat.com,
        kernel@...0n.name, krzysztof.kozlowski+dt@...aro.org,
        linux-kernel@...r.kernel.org, liuyun@...ngson.cn,
        loongarch@...ts.linux.dev, lvjianmin@...ngson.cn,
        robh+dt@...nel.org, tglx@...utronix.de, yang.lee@...ux.alibaba.com
Subject: Re: [PATCH v8 1/2] clocksource: loongson2_hpet: add hpet driver
 support

Le 03/11/2022 à 07:53, Yinbo Zhu a écrit :
> HPET (High Precision Event Timer) defines a new set of timers, which
> are used by the operating system to schedule threads, interrupt the
> kernel and interrupt the multimedia timer server. The operating
> system can assign different timers to different applications. By
> configuration, each timer can generate interrupt independently.
> 
> The Loongson-2 HPET module includes a main count and three comparators,
> all of which are 32 bits wide. Among the three comparators, only
> one comparator supports periodic interrupt, all three comparators
> support non periodic interrupts.
> 
> Signed-off-by: Yinbo Zhu <zhuyinbo-cXZgJK919ebM1kAEIRd3EQ@...lic.gmane.org>
> ---

[...]

Hi, a few nits below.

> +static int hpet_request_irq(struct clock_event_device *cd)
> +{
> +	unsigned long flags = IRQD_NO_BALANCING | IRQF_TIMER;
> +
> +	if (request_irq(cd->irq, hpet_irq_handler, flags, "hpet", NULL)) {
> +		pr_err("Failed to register hpet interrupt\n");

Maybe s/register/request/ ?

> +		return -1;
> +	}
> +
> +	disable_irq(cd->irq);
> +	irq_set_affinity(cd->irq, cd->cpumask);
> +	enable_irq(cd->irq);
> +
> +	return 0;
> +}
> +

[...]

> +static int __init loongson2_hpet_init(struct device_node *np)
> +{
> +	int ret;
> +	struct clk *clk;
> +
> +	hpet_mmio_base = of_iomap(np, 0);
> +	if (!hpet_mmio_base) {
> +		pr_err("hpet: unable to map loongson2 hpet registers\n");
> +		goto err;

'ret' is un-initialised at this point, and of_iomap() has failed, so 
there is no need to undo it in the error handling path.

> +	}
> +
> +	ret = -EINVAL;

Could be done at declataion, a few lines above.

> +	hpet_t0_irq = irq_of_parse_and_map(np, 0);
> +	if (hpet_t0_irq <= 0) {
> +		pr_err("hpet: unable to get IRQ from DT, %d\n", hpet_t0_irq);
> +		goto err;
> +	}
> +
> +	clk = of_clk_get(np, 0);
> +	if (!IS_ERR(clk)) {
> +		hpet_freq = clk_get_rate(clk);
> +		clk_put(clk);
> +	} else
> +		goto err;

Test for:
	if (IS_ERR(clk))
		goto err;

and keep :
	hpet_freq = clk_get_rate(clk);
	clk_put(clk);

with less indentation in the normal path?

CJ

> +
> +	hpet_irq_flags = HPET_TN_LEVEL;
> +
> +	loongson2_hpet_clocksource_init();
> +
> +	loongson2_hpet_clockevent_init();
> +
> +	return 0;
> +
> +err:
> +	iounmap(hpet_mmio_base);
> +	return ret;
> +}
> +
> +TIMER_OF_DECLARE(loongson2_hpet, "loongson,ls2k-hpet", loongson2_hpet_init);