Re: [RFC PATCH v3 1/5] rtc: add device selector for rtc_class_ops callbacks

[Ke Sun <sk.alvin.x@gmail.com>]

On 1/19/26 22:32, Danilo Krummrich wrote:
> On Fri Jan 16, 2026 at 5:21 PM CET, Ke Sun wrote:
>> diff --git a/drivers/rtc/dev.c b/drivers/rtc/dev.c
>> index baf1a8ca8b2b1..eddcc5a69db3b 100644
>> --- a/drivers/rtc/dev.c
>> +++ b/drivers/rtc/dev.c
>> @@ -410,7 +410,7 @@ static long rtc_dev_ioctl(struct file *file,
>>   		}
>>   		default:
>>   			if (rtc->ops->param_get)
>> -				err = rtc->ops->param_get(rtc->dev.parent, &param);
>> +				err = rtc->ops->param_get(rtc_ops_dev(rtc), &param);
>>   			else
>>   				err = -EINVAL;
>>   		}
> <snip>
>
>> +/**
>> + * rtc_ops_dev - Get the device pointer for RTC ops callbacks
>> + * @rtc: RTC device
>> + *
>> + * Returns &rtc->dev if RTC_OPS_USE_RTC_DEV flag is set,
>> + * otherwise returns rtc->dev.parent.
>> + */
>> +static inline struct device *rtc_ops_dev(struct rtc_device *rtc)
>> +{
>> +	if (test_bit(RTC_OPS_USE_RTC_DEV, &rtc->flags))
>> +		return &rtc->dev;
>> +	return rtc->dev.parent;
>> +}
> I understand that the idea is to gradually convert all drivers to use the RTC
> device, rather than it's parent device in RTC device callbacks.
>
> My main concern is that once that has been achieved it's still not what we want
> to have eventually, i.e. RTC device callbacks should ideally take a struct
> rtc_device as argument and not the embedded base struct device.
>
> I.e. we'd kick off a conversion process that won't reach the actual desired
> state.
Hi Danilo,

This is indeed an intermediate step.

Full cleanup is in progress, but it's large and untested. I'm working on a
complete cleanup involving ~190+ files across arch/, drivers/rtc/, and
drivers/virtio/. Most changes are straightforward interface replacements,
but some drivers need additional modifications. Given the scale, I haven't
fully tested everything and can't guarantee correctness yet.

The intermediate step enables gradual migration, allowing us to:
- Clean up and test each rtc driver incrementally
- Ensure correctness through gradual changes
- Avoid breaking existing functionality

Once all cleanup is complete and tested, changing all rtc_class_ops
callbacks to use struct rtc_device * will be much simpler and safer.

Currently there seem to be only these two approaches. I'm still waiting
for Alexandre's suggestion on how to proceed specifically, but haven't
received a response yet.

Best regard,
Ke Sun