Re: [PATCH net-next 1/5] dpll: zl3073x: clean up esync get/set and use zl3073x_out_is_ndiv()

[Ivan Vecera <ivecera@redhat.com>]

Hi Simon,

On 3/20/26 6:17 PM, Simon Horman wrote:
> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.
> 
> For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
> ---
> dpll: zl3073x: clean up esync get/set and use zl3073x_out_is_ndiv()
> 
> Return -EOPNOTSUPP early in esync_get callbacks when esync is not
> supported instead of conditionally populating the range at the end.
> This simplifies the control flow by removing the finish label/goto
> in the output variant and the conditional range assignment in both
> input and output variants.
> 
> Replace open-coded N-div signal format switch statements with
> zl3073x_out_is_ndiv() helper in esync_get, esync_set and
> frequency_set callbacks.
> 
>> diff --git a/drivers/dpll/zl3073x/dpll.c b/drivers/dpll/zl3073x/dpll.c
>> index a29f606318f6..79ef62d69a32 100644
>> --- a/drivers/dpll/zl3073x/dpll.c
>> +++ b/drivers/dpll/zl3073x/dpll.c
>> @@ -131,6 +131,12 @@ zl3073x_dpll_input_pin_esync_get(const struct dpll_pin *dpll_pin,
>>   	ref_id = zl3073x_input_pin_ref_get(pin->id);
>>   	ref = zl3073x_ref_state_get(zldev, ref_id);
>>
>> +	if (!pin->esync_control || zl3073x_ref_freq_get(ref) == 1)
>> +		return -EOPNOTSUPP;
>> +
>> +	esync->range = esync_freq_ranges;
>> +	esync->range_num = ARRAY_SIZE(esync_freq_ranges);
>> +
>>   	switch (FIELD_GET(ZL_REF_SYNC_CTRL_MODE, ref->sync_ctrl)) {
>>   	case ZL_REF_SYNC_CTRL_MODE_50_50_ESYNC_25_75:
>>   		esync->freq = ref->esync_n_div == ZL_REF_ESYNC_DIV_1HZ ? 1 : 0;
>> @@ -142,17 +148,6 @@ zl3073x_dpll_input_pin_esync_get(const struct dpll_pin *dpll_pin,
>>   		break;
>>   	}
>>
>> -	/* If the pin supports esync control expose its range but only
>> -	 * if the current reference frequency is > 1 Hz.
>> -	 */
>> -	if (pin->esync_control && zl3073x_ref_freq_get(ref) > 1) {
>> -		esync->range = esync_freq_ranges;
>> -		esync->range_num = ARRAY_SIZE(esync_freq_ranges);
>> -	} else {
>> -		esync->range = NULL;
>> -		esync->range_num = 0;
>> -	}
>> -
>>   	return 0;
>>   }
> 
> The refactoring changes the behavior when the reference frequency is 0 Hz.
> 
> The old code checked 'zl3073x_ref_freq_get(ref) > 1' which excluded both
> freq==0 and freq==1 from having the esync range exposed. The new code checks
> 'zl3073x_ref_freq_get(ref) == 1' which only excludes freq==1.
> 
> When freq==0 (which can happen when freq_base, freq_mult, or freq_ratio_m
> is 0), the old code would return 0 with esync->range=NULL and
> esync->range_num=0, while the new code returns 0 with
> esync->range=esync_freq_ranges and esync->range_num=1.
> 
> The removed comment documented the original intent: "if the current reference
> frequency is > 1 Hz". Should the new check be 'zl3073x_ref_freq_get(ref) <= 1'
> to preserve the original behavior for 0 Hz frequencies?
> 
>>
>> @@ -582,8 +577,8 @@ zl3073x_dpll_output_pin_esync_get(const struct dpll_pin *dpll_pin,
>>   	struct zl3073x_dpll_pin *pin = pin_priv;
>>   	const struct zl3073x_synth *synth;
>>   	const struct zl3073x_out *out;
>> +	u32 synth_freq, out_freq;
>>   	u8 clock_type, out_id;
>> -	u32 synth_freq;
>>
>>   	out_id = zl3073x_output_pin_out_get(pin->id);
>>   	out = zl3073x_out_state_get(zldev, out_id);
>> @@ -592,17 +587,19 @@ zl3073x_dpll_output_pin_esync_get(const struct dpll_pin *dpll_pin,
>>   	 * for N-division is also used for the esync divider so both cannot
>>   	 * be used.
>>   	 */
>> -	switch (zl3073x_out_signal_format_get(out)) {
>> -	case ZL_OUTPUT_MODE_SIGNAL_FORMAT_2_NDIV:
>> -	case ZL_OUTPUT_MODE_SIGNAL_FORMAT_2_NDIV_INV:
>> +	if (zl3073x_out_is_ndiv(out))
>>   		return -EOPNOTSUPP;
>> -	default:
>> -		break;
>> -	}
>>
>>   	/* Get attached synth frequency */
>>   	synth = zl3073x_synth_state_get(zldev, zl3073x_out_synth_get(out));
>>   	synth_freq = zl3073x_synth_freq_get(synth);
>> +	out_freq = synth_freq / out->div;
>> +
>> +	if (!pin->esync_control || out_freq == 1)
>> +		return -EOPNOTSUPP;
>> +
>> +	esync->range = esync_freq_ranges;
>> +	esync->range_num = ARRAY_SIZE(esync_freq_ranges);
>>
>>   	clock_type = FIELD_GET(ZL_OUTPUT_MODE_CLOCK_TYPE, out->mode);
>>   	if (clock_type != ZL_OUTPUT_MODE_CLOCK_TYPE_ESYNC) {
>> @@ -610,11 +607,11 @@ zl3073x_dpll_output_pin_esync_get(const struct dpll_pin *dpll_pin,
>>   		esync->freq = 0;
>>   		esync->pulse = 0;
>>
>> -		goto finish;
>> +		return 0;
>>   	}
>>
>>   	/* Compute esync frequency */
>> -	esync->freq = synth_freq / out->div / out->esync_n_period;
>> +	esync->freq = out_freq / out->esync_n_period;
>>
>>   	/* By comparing the esync_pulse_width to the half of the pulse width
>>   	 * the esync pulse percentage can be determined.
>> @@ -623,18 +620,6 @@ zl3073x_dpll_output_pin_esync_get(const struct dpll_pin *dpll_pin,
>>   	 */
>>   	esync->pulse = (50 * out->esync_n_width) / out->div;
>>
>> -finish:
>> -	/* Set supported esync ranges if the pin supports esync control and
>> -	 * if the output frequency is > 1 Hz.
>> -	 */
>> -	if (pin->esync_control && (synth_freq / out->div) > 1) {
>> -		esync->range = esync_freq_ranges;
>> -		esync->range_num = ARRAY_SIZE(esync_freq_ranges);
>> -	} else {
>> -		esync->range = NULL;
>> -		esync->range_num = 0;
>> -	}
>> -
>>   	return 0;
>>   }
> 
> Similar to the input variant, this changes the behavior for 0 Hz output
> frequencies.
> 
> The old code used '(synth_freq / out->div) > 1' to decide whether to expose
> the esync range, which excluded both out_freq==0 and out_freq==1. The new
> code uses 'out_freq == 1' for the early -EOPNOTSUPP return, only excluding
> out_freq==1.
> 
> When out_freq==0 (which can happen when synth_freq is 0 or synth_freq <
> out->div), the old code returned 0 with esync->range=NULL and
> esync->range_num=0, while the new code returns 0 with
> esync->range=esync_freq_ranges and esync->range_num=1.
> 
> The removed comment documented the intent: "if the output frequency is > 1
> Hz". Should this also use 'out_freq <= 1' to maintain consistency with the
> original behavior?
> 
> [ ... ]
> 

The frequency for both input and output pins cannot be zero... Cannot be
set to 0 and device never returns configured frequency to be 0.

I can modify the lines to be:

if (!pin->esync_control || out_freq <= 1)
	return -EOPNOTSUPP;

but it is needless - but let me know.

Thanks,
Ivan