linux-kernel - Re: [PATCH V1] rtc: loongson: Add missing alarm notifications for ACPI RTC events

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Message-ID: <9b32fba8-a096-416a-abba-338ef414def7@loongson.cn>
Date: Fri, 9 May 2025 16:27:41 +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 V1] rtc: loongson: Add missing alarm notifications for
 ACPI RTC events


On 2025/5/9 16:06, Liu Dalin wrote:
>
>
> 在 2025/5/9 15:12, Binbin Zhou 写道:
>> Hi:
>>
>> On 2025/5/9 09:40, 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.
>>>
>>> Fixes: 1b733a9ebc3d ("rtc: Add rtc driver for the Loongson family 
>>> chips")
>>> Signed-off-by: Liu Dalin <liudalin@...insec.com.cn>
>> Technically I don't think this is a compliant patch, firstly this 
>> patch should be V2 and also you should add "Changlog" for describing 
>> the differences from the previous patch.
>> Anyway, it's good to me.
>
> Ok! There is another problem, if regmap_write(priv->regmap,
> TOY_MATCH0_REG, 0) move to the end of loongson_rtc_handler as 
> 09471d8f5b39("rtc: loongson: clear TOY_MATCH0_REG in 
> loongson_rtc_isr()"), the interrupt also can be triggered multiple times.
>
> So the regmap_write(priv->regmap,TOY_MATCH0_REG, 0) is move behind of 
> rtc_update_irq by me, then the interrupt was triggered OK.
>
> Is there any problem ?

It is ok. That's where I added it when I suggested it before.

Thanks.
Binbin

>
>>
>> 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
>>
>>
>>