Re: [PATCH net-next v3 1/2] dpll: zl3073x: update all DPLL channels on ref_sync_set

[Petr Oros <poros@redhat.com>]

On 8/7/26 11:59, Ivan Vecera wrote:
> zl3073x_dpll_input_pin_ref_sync_set() excludes the sync source from
> automatic reference selection by setting its priority to NONE, but
> currently only does this on the single DPLL channel whose pin_priv
> was passed to the callback.
>
> Since input pins are registered with every DPLL channel, the datasheet
> recommends covering all channels to prevent the sync source from
> remaining a selectable candidate on the other channels. This is
> a preparation for the following patch which changes the DPLL core to
> invoke pin-level set callbacks only through the pin owner's reference
> instead of iterating over all registered DPLL devices.
>
> Replace the single-channel priority write with a list_for_each_entry()
> loop over all DPLL channels. Each channel's lock is acquired
> individually for its read-modify-write sequence. The guard(mutex) is
> replaced with explicit mutex_lock/mutex_unlock to allow releasing the
> owner's lock before iterating, avoiding nested locking of the same
> mutex class. A change notification is sent for the sync pin if any
> channel's priority was actually modified.
>
> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> ---
>   drivers/dpll/zl3073x/dpll.c | 58 ++++++++++++++++++++++++++++++-------
>   1 file changed, 48 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/dpll/zl3073x/dpll.c b/drivers/dpll/zl3073x/dpll.c
> index 0488ae6ac486c8..83bd3027dbaa1e 100644
> --- a/drivers/dpll/zl3073x/dpll.c
> +++ b/drivers/dpll/zl3073x/dpll.c
> @@ -263,9 +263,10 @@ zl3073x_dpll_input_pin_ref_sync_set(const struct dpll_pin *dpll_pin,
>   	u8 mode, ref_id, sync_ref_id;
>   	struct zl3073x_chan chan;
>   	struct zl3073x_ref ref;
> +	bool sync_ntf = false;
>   	int rc;
>   
> -	guard(mutex)(&zldpll->lock);
> +	mutex_lock(&zldpll->lock);
>   
>   	ref_id = zl3073x_input_pin_ref_get(pin->id);
>   	sync_ref_id = zl3073x_input_pin_ref_get(sync_pin->id);
> @@ -285,17 +286,20 @@ zl3073x_dpll_input_pin_ref_sync_set(const struct dpll_pin *dpll_pin,
>   		if (sync_freq > 8000) {
>   			NL_SET_ERR_MSG(extack,
>   				       "sync frequency must be 8 kHz or less");
> -			return -EINVAL;
> +			rc = -EINVAL;
> +			goto unlock;
>   		}
>   		if (ref_freq < 1000) {
>   			NL_SET_ERR_MSG(extack,
>   				       "clock frequency must be 1 kHz or more");
> -			return -EINVAL;
> +			rc = -EINVAL;
> +			goto unlock;
>   		}
>   		if (ref_freq <= sync_freq) {
>   			NL_SET_ERR_MSG(extack,
>   				       "clock frequency must be higher than sync frequency");
> -			return -EINVAL;
> +			rc = -EINVAL;
> +			goto unlock;
>   		}
>   
>   		zl3073x_ref_sync_pair_set(&ref, sync_ref_id);
> @@ -308,20 +312,54 @@ zl3073x_dpll_input_pin_ref_sync_set(const struct dpll_pin *dpll_pin,
>   
>   	rc = zl3073x_ref_state_set(zldev, ref_id, &ref);
>   	if (rc)
> -		return rc;
> +		goto unlock;
>   
> -	/* Exclude sync source from automatic reference selection by setting
> -	 * its priority to NONE. On disconnect the priority is left as NONE
> -	 * and the user must explicitly make the pin selectable again.
> +	/* All code paths accessing per-channel reference priorities are
> +	 * serialized by the subsystem dpll_lock, so it is safe to release
> +	 * our lock here before iterating over the other channels.
>   	 */
> -	if (state == DPLL_PIN_STATE_CONNECTED) {
> +	mutex_unlock(&zldpll->lock);
> +
> +	if (state != DPLL_PIN_STATE_CONNECTED)
> +		return 0;
> +
> +	/* The datasheet recommends excluding the sync source from automatic
> +	 * reference selection by setting its priority to NONE on all DPLL
> +	 * channels. This is advisory - the ref sync pair is already
> +	 * configured, so a failure here is not fatal. On disconnect the
> +	 * priority is left as NONE and the user must explicitly make the
> +	 * pin selectable again.
> +	 */
> +	list_for_each_entry(zldpll, &zldev->dplls, list) {
> +		u8 prio;
> +
> +		mutex_lock(&zldpll->lock);
> +
>   		chan = *zl3073x_chan_state_get(zldev, zldpll->id);
> +		prio = zl3073x_chan_ref_prio_get(&chan, sync_ref_id);
> +		if (prio == ZL_DPLL_REF_PRIO_NONE) {
> +			mutex_unlock(&zldpll->lock);
> +			continue; /* Ref is already non-selectable */
> +		}
> +
>   		zl3073x_chan_ref_prio_set(&chan, sync_ref_id,
>   					  ZL_DPLL_REF_PRIO_NONE);
> -		return zl3073x_chan_state_set(zldev, zldpll->id, &chan);
> +		if (zl3073x_chan_state_set(zldev, zldpll->id, &chan))
> +			dev_warn(zldev->dev,
> +				 "Failed to set ref prio on DPLL%u\n",
> +				 zldpll->id);
> +		else
> +			sync_ntf = true;
> +
> +		mutex_unlock(&zldpll->lock);
>   	}
> +	if (sync_ntf)
> +		__dpll_pin_change_ntf(sync_pin->dpll_pin);
>   
>   	return 0;
> +unlock:
> +	mutex_unlock(&zldpll->lock);
> +	return rc;
>   }
>   
>   static int

Reviewed-by: Petr Oros <poros@redhat.com>