linux-kernel - Re: [PATCH net-next v2 1/6] dpll: zl3073x: Store raw register values instead of parsed state

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Message-ID: <886723c3-ff9e-43cf-a1da-021f1ff088ab@linux.dev>
Date: Wed, 12 Nov 2025 14:12:05 +0000
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Ivan Vecera <ivecera@...hat.com>, netdev@...r.kernel.org
Cc: Petr Oros <poros@...hat.com>,
 Prathosh Satish <Prathosh.Satish@...rochip.com>,
 Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
 Jiri Pirko <jiri@...nulli.us>, Michal Schmidt <mschmidt@...hat.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 1/6] dpll: zl3073x: Store raw register values
 instead of parsed state

On 11/11/2025 18:12, Ivan Vecera wrote:
> The zl3073x_ref, zl3073x_out and zl3073x_synth structures
> previously stored state that was parsed from register reads. This
> included values like boolean 'enabled' flags, synthesizer selections,
> and pre-calculated frequencies.
> 
> This commit refactors the state management to store the raw register
> values directly in these structures. The various inline helper functions
> are updated to parse these raw values on-demand using FIELD_GET.
> 
> Reviewed-by: Petr Oros <poros@...hat.com>
> Tested-by: Prathosh Satish <Prathosh.Satish@...rochip.com>
> Signed-off-by: Ivan Vecera <ivecera@...hat.com>
> ---
>   drivers/dpll/zl3073x/core.c | 81 ++++++++++++-------------------------
>   drivers/dpll/zl3073x/core.h | 61 ++++++++++++++++------------
>   2 files changed, 60 insertions(+), 82 deletions(-)
> 
> diff --git a/drivers/dpll/zl3073x/core.c b/drivers/dpll/zl3073x/core.c
> index e42e527813cf8..50c1fe59bc7f0 100644
> --- a/drivers/dpll/zl3073x/core.c
> +++ b/drivers/dpll/zl3073x/core.c
> @@ -598,25 +598,22 @@ int zl3073x_write_hwreg_seq(struct zl3073x_dev *zldev,
>    * @zldev: pointer to zl3073x_dev structure
>    * @index: input reference index to fetch state for
>    *
> - * Function fetches information for the given input reference that are
> - * invariant and stores them for later use.
> + * Function fetches state for the given input reference and stores it for
> + * later user.
>    *
>    * Return: 0 on success, <0 on error
>    */
>   static int
>   zl3073x_ref_state_fetch(struct zl3073x_dev *zldev, u8 index)
>   {
> -	struct zl3073x_ref *input = &zldev->ref[index];
> -	u8 ref_config;
> +	struct zl3073x_ref *ref = &zldev->ref[index];
>   	int rc;
>   
>   	/* If the input is differential then the configuration for N-pin
>   	 * reference is ignored and P-pin config is used for both.
>   	 */
> -	if (zl3073x_is_n_pin(index) &&
> -	    zl3073x_ref_is_diff(zldev, index - 1)) {
> -		input->enabled = zl3073x_ref_is_enabled(zldev, index - 1);
> -		input->diff = true;
> +	if (zl3073x_is_n_pin(index) && zl3073x_ref_is_diff(zldev, index - 1)) {
> +		memcpy(ref, &zldev->ref[index - 1], sizeof(*ref));

Oh, it's not obvious from the code that it's actually safe, unless
reviewer remembers that N-pins have only even indexes.
Have you thought of adding an abstraction for differential pair pins?

>   
>   		return 0;
>   	}