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Date: Mon, 19 Jan 2026 15:32:23 +0100
Message-Id: <DFSN0O9RRVD6.1LCI38JKGO1R0@kernel.org>
To: "Ke Sun" <sunke@kylinos.cn>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [RFC PATCH v3 1/5] rtc: add device selector for rtc_class_ops
 callbacks
Cc: "Alexandre Belloni" <alexandre.belloni@bootlin.com>, "Miguel Ojeda"
 <ojeda@kernel.org>, "Boqun Feng" <boqun.feng@gmail.com>, "Gary Guo"
 <gary@garyguo.net>, =?utf-8?q?Bj=C3=B6rn_Roy_Baron?=
 <bjorn3_gh@protonmail.com>, "Benno Lossin" <lossin@kernel.org>, "Andreas
 Hindborg" <a.hindborg@kernel.org>, "Alice Ryhl" <aliceryhl@google.com>,
 "Trevor Gross" <tmgross@umich.edu>, <linux-rtc@vger.kernel.org>,
 <rust-for-linux@vger.kernel.org>, "Alvin Sun" <sk.alvin.x@gmail.com>, "Greg
 Kroah-Hartman" <gregkh@linuxfoundation.org>, "Rafael J. Wysocki"
 <rafael@kernel.org>
References: <20260116162203.296844-1-sunke@kylinos.cn>
 <20260116162203.296844-2-sunke@kylinos.cn>
In-Reply-To: <20260116162203.296844-2-sunke@kylinos.cn>

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 =3D rtc->ops->param_get(rtc->dev.parent, &param);
> +				err =3D rtc->ops->param_get(rtc_ops_dev(rtc), &param);
>  			else
>  				err =3D -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 R=
TC
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.