linux-kernel - Re: [PATCH v2] clocksource/drivers/sp804: avoid error on multiple instances

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Message-ID: <6c148e83-3244-d47a-37e3-1a1f01fe35bc@arm.com>
Date:   Fri, 6 May 2022 17:41:55 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Andre Przywara <andre.przywara@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Russell King <linux@...linux.org.uk>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Zhen Lei <thunder.leizhen@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clocksource/drivers/sp804: avoid error on multiple
 instances

On 2022-05-06 17:25, Andre Przywara wrote:
> When a machine sports more than one SP804 timer instance, we only bring
> up the first one, since multiple timers of the same kind are not useful
> to Linux. As this is intentional behaviour, we should not return an
> error message, as we do today:
> ===============
> [    0.000800] Failed to initialize '/bus@...0000/motherboard-bus@...0000/iofpga-bus@...000000/timer@...000': -22
> ===============
> 
> Replace the -EINVAL return with a debug message and return 0 instead.
> 
> Also we do not reach the init function anymore if the DT node is
> disabled (as this is now handled by OF_DECLARE), so remove the explicit
> check for that case.
> 
> This fixes a long standing bogus error when booting ARM's fastmodels.

Reviewed-by: Robin Murphy <robin.murphy@....com>

> Signed-off-by: Andre Przywara <andre.przywara@....com>
> ---
> Changelog v1 .. v2:
> - demote pr_info() to pr_debug(), to avoid output at all
> - use %pOF and reword message
> 
>   drivers/clocksource/timer-sp804.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-sp804.c b/drivers/clocksource/timer-sp804.c
> index 401d592e85f5a..e6a87f4af2b50 100644
> --- a/drivers/clocksource/timer-sp804.c
> +++ b/drivers/clocksource/timer-sp804.c
> @@ -259,6 +259,11 @@ static int __init sp804_of_init(struct device_node *np, struct sp804_timer *time
>   	struct clk *clk1, *clk2;
>   	const char *name = of_get_property(np, "compatible", NULL);
>   
> +	if (initialized) {
> +		pr_debug("%pOF: skipping further SP804 timer device\n", np);
> +		return 0;
> +	}
> +
>   	base = of_iomap(np, 0);
>   	if (!base)
>   		return -ENXIO;
> @@ -270,11 +275,6 @@ static int __init sp804_of_init(struct device_node *np, struct sp804_timer *time
>   	writel(0, timer1_base + timer->ctrl);
>   	writel(0, timer2_base + timer->ctrl);
>   
> -	if (initialized || !of_device_is_available(np)) {
> -		ret = -EINVAL;
> -		goto err;
> -	}
> -
>   	clk1 = of_clk_get(np, 0);
>   	if (IS_ERR(clk1))
>   		clk1 = NULL;