[PATCH] rtc: amlogic-a4: clear unsupported update interrupt feature

[PATCH] rtc: amlogic-a4: clear unsupported update interrupt feature

[Xianwei Zhao via B4 Relay]

From: Xianwei Zhao <xianwei.zhao@amlogic.com>

The Amlogic A4 RTC does not support update interrupt. Clear
RTC_FEATURE_UPDATE_INTERRUPT before registering the RTC device to
prevent userspace from enabling an unsupported RTC UIE function.

Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
---
Clear RTC_FEATURE_UPDATE_INTERRUPT before registering the RTC device.
---
 drivers/rtc/rtc-amlogic-a4.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/rtc/rtc-amlogic-a4.c b/drivers/rtc/rtc-amlogic-a4.c
index 50938c35af36..116cf095a9e9 100644
--- a/drivers/rtc/rtc-amlogic-a4.c
+++ b/drivers/rtc/rtc-amlogic-a4.c
@@ -379,6 +379,7 @@ static int aml_rtc_probe(struct platform_device *pdev)
 	rtc->rtc_dev->ops = &aml_rtc_ops;
 	rtc->rtc_dev->range_min = 0;
 	rtc->rtc_dev->range_max = U32_MAX;
+	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtc_dev->features);
 
 	return devm_rtc_register_device(rtc->rtc_dev);
 }

---
base-commit: 851d961ff248218f681c53cf0f7f08cf8201a117
change-id: 20260624-rtc-feature-03ce3f3843a9

Best regards,
-- 
Xianwei Zhao <xianwei.zhao@amlogic.com>

Re: [PATCH] rtc: amlogic-a4: clear unsupported update interrupt feature

[Alexandre Belloni]

Hello,

On 24/06/2026 07:24:34+0000, Xianwei Zhao via B4 Relay wrote:
> From: Xianwei Zhao <xianwei.zhao@amlogic.com>
> 
> The Amlogic A4 RTC does not support update interrupt. Clear
> RTC_FEATURE_UPDATE_INTERRUPT before registering the RTC device to
> prevent userspace from enabling an unsupported RTC UIE function.
> 

Because the driver supports alarms, it should support UIE. Is there any
reason the RTC can't handle arming alarms every seconds?
There are some that would only support alarms avery 2s, in that case,
please set RTC_FEATURE_ALARM_RES_2S.

> Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
> ---
> Clear RTC_FEATURE_UPDATE_INTERRUPT before registering the RTC device.
> ---
>  drivers/rtc/rtc-amlogic-a4.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/rtc/rtc-amlogic-a4.c b/drivers/rtc/rtc-amlogic-a4.c
> index 50938c35af36..116cf095a9e9 100644
> --- a/drivers/rtc/rtc-amlogic-a4.c
> +++ b/drivers/rtc/rtc-amlogic-a4.c
> @@ -379,6 +379,7 @@ static int aml_rtc_probe(struct platform_device *pdev)
>  	rtc->rtc_dev->ops = &aml_rtc_ops;
>  	rtc->rtc_dev->range_min = 0;
>  	rtc->rtc_dev->range_max = U32_MAX;
> +	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtc_dev->features);
>  
>  	return devm_rtc_register_device(rtc->rtc_dev);
>  }
> 
> ---
> base-commit: 851d961ff248218f681c53cf0f7f08cf8201a117
> change-id: 20260624-rtc-feature-03ce3f3843a9
> 
> Best regards,
> -- 
> Xianwei Zhao <xianwei.zhao@amlogic.com>
> 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com