linux-kernel - Re: [PATCH 2/7] clocksource: timer-npcm7xx: Enable timer 1 clock before use

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Date:   Thu, 28 Apr 2022 09:11:58 +0000
From:   Zev Weiss <zweiss@...inix.com>
To:     Jonathan Neuschäfer <j.neuschaefer@....net>
CC:     "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Patrick Venture <venture@...gle.com>,
        Michael Turquette <mturquette@...libre.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Avi Fishman <avifishman70@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Tali Perry <tali.perry1@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Guenter Roeck <linux@...ck-us.net>,
        Tomer Maimon <tmaimon77@...il.com>
Subject: Re: [PATCH 2/7] clocksource: timer-npcm7xx: Enable timer 1 clock
 before use

On Fri, Apr 22, 2022 at 11:30:07AM PDT, Jonathan Neuschäfer wrote:
>In the WPCM450 SoC, the clocks for each timer can be gated individually.
>To prevent the timer 1 clock from being gated, enable it explicitly.
>
>Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@....net>
>---
> drivers/clocksource/timer-npcm7xx.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/clocksource/timer-npcm7xx.c b/drivers/clocksource/timer-npcm7xx.c
>index a00520cbb660a..974269b6b0c36 100644
>--- a/drivers/clocksource/timer-npcm7xx.c
>+++ b/drivers/clocksource/timer-npcm7xx.c
>@@ -188,17 +188,29 @@ static void __init npcm7xx_clocksource_init(void)
>
> static int __init npcm7xx_timer_init(struct device_node *np)
> {
>+	struct clk *clk;
> 	int ret;
>
> 	ret = timer_of_init(np, &npcm7xx_to);
>-	if (ret)
>+	if (ret) {
>+		pr_warn("timer_of_init failed: %d\n", ret);

This seems like a somewhat opaque message to emit, especially given this
file's lack of a pr_fmt() definition -- maybe add a %pOF so it's
slightly easier to trace back to the device it stems from?

> 		return ret;
>+	}
>
> 	/* Clock input is divided by PRESCALE + 1 before it is fed */
> 	/* to the counter */
> 	npcm7xx_to.of_clk.rate = npcm7xx_to.of_clk.rate /
> 		(NPCM7XX_Tx_MIN_PRESCALE + 1);
>
>+	/* Enable the clock for timer1, if it exists */
>+	clk = of_clk_get(np, 1);
>+	if (clk) {
>+		if (!IS_ERR(clk))
>+			clk_prepare_enable(clk);
>+		else
>+			pr_warn("Failed to get clock for timer1: %pe", clk);

Likewise here (though to a slightly lesser extent).

>+	}
>+
> 	npcm7xx_clocksource_init();
> 	npcm7xx_clockevents_init();
>
>--
>2.35.1
>