linux-kernel - Re: [PATCH V2] rtc: loongson: Add missing alarm notifications for ACPI RTC events

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Message-ID: <6f47e397-8877-4412-bebd-0314a6b46908@loongson.cn>
Date: Tue, 13 May 2025 15:32:41 +0800
From: Binbin Zhou <zhoubinbin@...ngson.cn>
To: Liu Dalin <liudalin@...insec.com.cn>, alexandre.belloni@...tlin.com,
 wangming01@...ngson.cn
Cc: chenhuacai@...nel.org, gaojuxin@...ngson.cn, git@...0n.name,
 jiaxun.yang@...goat.com, keguang.zhang@...il.com, lixuefeng@...ngson.cn,
 linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] rtc: loongson: Add missing alarm notifications for
 ACPI RTC events


On 2025/5/9 16:44, Liu Dalin wrote:
> When an application sets and enables an alarm on Loongson RTC devices,
> the alarm notification fails to propagate to userspace because the
> ACPI event handler omits calling rtc_update_irq().
>
> As a result, processes waiting via select() or poll() on RTC device
> files fail to receive alarm notifications.
>
> The ACPI interrupt is also triggered multiple times. In loongson_rtc_handler,
> we need to clear TOY_MATCH0_REG to resolve this issue.
>
> Fixes: 09471d8f5b39 ("rtc: loongson: clear TOY_MATCH0_REG in loongson_rtc_isr()")
> Fixes: 1b733a9ebc3d ("rtc: Add rtc driver for the Loongson family chips")
> Signed-off-by: Liu Dalin <liudalin@...insec.com.cn>
Reviewed-by: Binbin Zhou <zhoubinbin@...ngson.cn>
> ---
>   drivers/rtc/rtc-loongson.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/drivers/rtc/rtc-loongson.c b/drivers/rtc/rtc-loongson.c
> index 97e5625c064c..2ca7ffd5d7a9 100644
> --- a/drivers/rtc/rtc-loongson.c
> +++ b/drivers/rtc/rtc-loongson.c
> @@ -129,6 +129,14 @@ static u32 loongson_rtc_handler(void *id)
>   {
>   	struct loongson_rtc_priv *priv = (struct loongson_rtc_priv *)id;
>   
> +	rtc_update_irq(priv->rtcdev, 1, RTC_AF | RTC_IRQF);
> +
> +	/*
> +	 * The TOY_MATCH0_REG should be cleared 0 here,
> +	 * otherwise the interrupt cannot be cleared.
> +	 */
> +	regmap_write(priv->regmap, TOY_MATCH0_REG, 0);
> +
>   	spin_lock(&priv->lock);
>   	/* Disable RTC alarm wakeup and interrupt */
>   	writel(readl(priv->pm_base + PM1_EN_REG) & ~RTC_EN,
Thanks.
Binbin