linux-kernel - Re: [PATCH v2] clocksource/drivers/tango

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Date:	Wed, 7 Oct 2015 14:31:59 +0200
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Marc Gonzalez <marc_gonzalez@...madesigns.com>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Mans Rullgard <mans@...sr.com>, Mason <slash.tmp@...e.fr>
Subject: Re: [PATCH v2] clocksource/drivers/tango_xtal: Add new timer for
 Tango SoCs

On 10/07/2015 01:35 PM, Marc Gonzalez wrote:
> Sigma Designs Tango platforms provide a 27 MHz crystal oscillator.
> Use it for clocksource, sched_clock, and delay_timer.
>
> Signed-off-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>
> ---
> AFAICS, clocksource_register_hz does not report failures via its
> return value (always 0) but writes warnings to stdout?

Yeah, it returns always 0. I suggest you assume it is returning an error 
code, that will be safer for future changes in the framework (if any).

> Open question: can I call register_current_timer_delay,
> sched_clock_register, clocksource_register_hz in any order?
> ---

Yes, I think so. Thomas ?

[ ... ]

> +static void __init tango_clocksource_init(struct device_node *np)
> +{
> +	struct clk *clk = of_clk_get(np, 0);
> +	unsigned int xtal_freq = clk_get_rate(clk);
> +	xtal_in_cnt = of_iomap(np, 0);
> +	if (xtal_in_cnt == NULL)
> +		panic("%s: of_iomap failed\n", np->full_name);

   ^^^^^^^^^^^

That does not comply with the Linux kernel coding style.

	xtal_in_cnt = of_iomap(np, 0);
	if (!xtal_in_cnt) {
		pr_err("Argh!");
		return;
	}

	clk = of_clk_get(np, 0);
	if (!clk) {
		pr_err("grumf!");
		return;
	}

	freq = clk_get_rate(clk);


> +
> +	delay_timer.freq = xtal_freq;
> +	delay_timer.read_current_timer = read_xtal_counter;
> +	register_current_timer_delay(&delay_timer);
> +	sched_clock_register(read_sched_clock, 32, xtal_freq);
> +	clocksource_register_hz(&tango_xtal, xtal_freq);

ret = clocksource_register_hz(&tango_xtal, xtal_freq);
if (ret) {
	pr_err("oups!");
	return;
}



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