netdev - RE: [Intel-wired-lan] [PATCH net-next 3/4] dpll: netlink/core: add support for pin-dpll signal phase offset/adjust

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Message-ID: <DM6PR11MB46573D01E85D027150761CC99BCBA@DM6PR11MB4657.namprd11.prod.outlook.com>
Date: Wed, 4 Oct 2023 09:13:23 +0000
From: "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@...el.com>
To: Jiri Pirko <jiri@...nulli.us>
CC: Vadim Fedorenko <vadim.fedorenko@...ux.dev>, "corbet@....net"
	<corbet@....net>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, "Brandeburg, Jesse"
	<jesse.brandeburg@...el.com>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>, "kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>, "davem@...emloft.net"
	<davem@...emloft.net>
Subject: RE: [Intel-wired-lan] [PATCH net-next 3/4] dpll: netlink/core: add
 support for pin-dpll signal phase offset/adjust

>From: Jiri Pirko <jiri@...nulli.us>
>Sent: Tuesday, October 3, 2023 7:19 PM
>
>Tue, Oct 03, 2023 at 04:29:13PM CEST, arkadiusz.kubalewski@...el.com wrote:
>>>From: Jiri Pirko <jiri@...nulli.us>
>>>Sent: Tuesday, October 3, 2023 8:27 AM
>>>To: Kubalewski, Arkadiusz <arkadiusz.kubalewski@...el.com>
>>>
>>>Tue, Oct 03, 2023 at 01:10:39AM CEST, arkadiusz.kubalewski@...el.com
>>>wrote:
>>>>>From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf Of
>>>>>Vadim Fedorenko
>>>>>Sent: Monday, October 2, 2023 5:09 PM
>>>>>
>>>>>On 02/10/2023 16:04, Jiri Pirko wrote:
>>>>>> Mon, Oct 02, 2023 at 04:32:30PM CEST, arkadiusz.kubalewski@...el.com
>>>>>> wrote:
>>>>>>>> From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
>>>>>>>> Sent: Wednesday, September 27, 2023 8:09 PM
>>>>>>>>
>>>>>>>> On 27/09/2023 10:24, Arkadiusz Kubalewski wrote:
>>>>>>>>> Add callback op (get) for pin-dpll phase-offset measurment.
>>>>>>>>> Add callback ops (get/set) for pin signal phase adjustment.
>>>>>>>>> Add min and max phase adjustment values to pin proprties.
>>>>>>>>> Invoke get callbacks when filling up the pin details to provide user
>>>>>>>>> with phase related attribute values.
>>>>>>>>> Invoke phase-adjust set callback when phase-adjust value is provided
>>>>>>>>> for
>>>>>>>>> pin-set request.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
>>>>>>>>
>>>>>>>> [...]
>>>>>>>>
>>>>>>>>> +static int
>>>>>>>>> +dpll_pin_phase_adj_set(struct dpll_pin *pin, struct nlattr
>>>>>>>>> *phase_adj_attr,
>>>>>>>>> +		       struct netlink_ext_ack *extack)
>>>>>>>>> +{
>>>>>>>>> +	struct dpll_pin_ref *ref;
>>>>>>>>> +	unsigned long i;
>>>>>>>>> +	s32 phase_adj;
>>>>>>>>> +	int ret;
>>>>>>>>> +
>>>>>>>>> +	phase_adj = nla_get_s32(phase_adj_attr);
>>>>>>>>> +	if (phase_adj > pin->prop->phase_range.max ||
>>>>>>>>> +	    phase_adj < pin->prop->phase_range.min) {
>>>>>>>>> +		NL_SET_ERR_MSG(extack, "phase adjust value not
>>>>>>>>> supported");
>>>>>>>>> +		return -EINVAL;
>>>>>>>>> +	}
>>>>>>>>> +	xa_for_each(&pin->dpll_refs, i, ref) {
>>>>>>>>> +		const struct dpll_pin_ops *ops = dpll_pin_ops(ref);
>>>>>>>>> +		struct dpll_device *dpll = ref->dpll;
>>>>>>>>> +
>>>>>>>>> +		if (!ops->phase_adjust_set)
>>>>>>>>> +			return -EOPNOTSUPP;
>>>>>>>>
>>>>>>>> I'm thinking about this part. We can potentially have dpll devices
>>>>>>>> with
>>>>>>>> different expectations on phase adjustments, right? And if one of
>>>>>>>> them
>>>>>>>> won't be able to adjust phase (or will fail in the next line), then
>>>>>>>> netlink will return EOPNOTSUPP while _some_ of the devices will be
>>>>>>>> adjusted. Doesn't look great. Can we think about different way to
>>>>>>>> apply
>>>>>>>> the change?
>>>>>>>>
>>>>>>>
>>>>>>> Well makes sense to me.
>>>>>>>
>>>>>>> Does following makes sense as a fix?
>>>>>>> We would call op for all devices which has been provided with the op.
>>>>>>> If device has no op -> add extack error, continue
>>>>>>
>>>>>> Is it real to expect some of the device support this and others don't?
>>>>>> Is it true for ice?
>>>>>> If not, I would got for all-or-nothing here.
>>>>>>
>>>>>
>>>>>But nothing blocks vendors to provide such configuration. Should we
>>>>>rollback the configuration? Otherwise we can easily make it
>>>>>inconsistent.
>>>>
>>>>Good point, in such case rollback might be required.
>>>>
>>>>>
>>>>>I'm more thinking of checking if all the devices returned error (or
>>>>>absence of operation callback) and then return error instead of 0 with
>>>>>extack filled in.
>>>>>
>>>>
>>>>Well, what if different devices would return different errors?
>>>>In general we would have to keep track of the error values returned in
>>>>such case.. Assuming one is different than the other - still need to
>>>>error
>>>>extack them out? I guess it would be easier to return common error if
>>>there
>>>
>>>In this case, it is common to return the first error hit and bail out,
>>>not trying the rest.
>>>
>>
>>OK, so now I see it like this:
>>-> check if all device implement callback, if not return EOPNOTSUPP;
>>-> get old phase_adjust
>>-> if new == old, return EINVAL
>
>0 would be better, no? User has what he desired.
>

Yes, that makes sense.

>
>>-> for each device: call phase_adjust_set, if fails, rollback all previous
>>   successful attempts and return the failure code
>
>That would work.
>

Great, just sent v2.
Thanks!
Arkadiusz

>
>>?
>>
>>Thank you!
>>Arkadiusz
>>
>>>
>>>>were only failures and let the driver fill the errors on extack, smt
>>>>like:
>>>>
>>>>	int miss_cb_num = 0, dev_num = 0, err_num;
>>>>
>>>>	xa_for_each(&pin->dpll_refs, i, ref) {
>>>>		const struct dpll_pin_ops *ops = dpll_pin_ops(ref);
>>>>		struct dpll_device *dpll = ref->dpll;
>>>>
>>>>		dev_num++;
>>>>		if (!ops->phase_adjust_set) {
>>>>			miss_cb_num++;
>>>>			continue;
>>>>		}
>>>>		ret = ops->phase_adjust_set(pin,
>>>>					dpll_pin_on_dpll_priv(dpll, pin),
>>>>					dpll, dpll_priv(dpll), phase_adj,
>>>>					extack);
>>>>		if (ret)
>>>>			err_num++;
>>>>	}
>>>>	if (dev_num == miss_cb_num)
>>>>		return -EOPNOTSUPP;
>>>>	if (dev_num == err_num)
>>>>		return -EINVAL;
>>>>	__dpll_pin_change_ntf(pin);
>>>>	return 0;
>>>>
>>>>??
>>>>
>>>>Thank you!
>>>>Arkadiusz
>>>>
>>>>>>
>>>>>>> If device fails to set -> add extack error, continue
>>>>>>> Function always returns 0.
>>>>>>>
>>>>>>> Thank you!
>>>>>>> Arkadiusz
>>>>>>>
>>>>>>>>
>>>>>>>>> +		ret = ops->phase_adjust_set(pin,
>>>>>>>>> +					    dpll_pin_on_dpll_priv(dpll, pin),
>>>>>>>>> +					    dpll, dpll_priv(dpll), phase_adj,
>>>>>>>>> +					    extack);
>>>>>>>>> +		if (ret)
>>>>>>>>> +			return ret;
>>>>>>>>> +	}
>>>>>>>>> +	__dpll_pin_change_ntf(pin);
>>>>>>>>> +
>>>>>>>>> +	return 0;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>
>>>>>_______________________________________________
>>>>>Intel-wired-lan mailing list
>>>>>Intel-wired-lan@...osl.org
>>>>>https://lists.osuosl.org/mailman/listinfo/intel-wired-lan
>>

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