-----Original Message-----
From: Richard Cochran <richardcochran@gmail.com>
Sent: Tuesday, March 24, 2020 9:20 PM
To: Y.b. Lu <yangbo.lu@nxp.com>
Cc: Vladimir Oltean <olteanv@gmail.com>; lkml
[off-list ref]; netdev [off-list ref]; David S .
Miller [off-list ref]; Vladimir Oltean [off-list ref];
Claudiu Manoil [off-list ref]; Andrew Lunn [off-list ref];
Vivien Didelot [off-list ref]; Florian Fainelli
[off-list ref]; Alexandre Belloni [off-list ref];
Microchip Linux Driver Support [off-list ref]
Subject: Re: [PATCH 6/6] ptp_ocelot: support 4 programmable pins

On Tue, Mar 24, 2020 at 05:21:27AM +0000, Y.b. Lu wrote:

quoted

In my one previous patch, I was suggested to implement PPS with

programmable pin periodic clock function.

quoted

But I didn’t find how should PPS be implemented with periodic clock

function after checking ptp driver.

quoted

https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchw
ork.ozlabs.org%2Fpatch%2F1215464%2F&data=02%7C01%7Cyangbo.lu
%40nxp.com%7Cbfdbd209ae014cd8484b08d7cff60c13%7C686ea1d3bc2b4c6
fa92cd99c5c301635%7C0%7C0%7C637206527981191161&sdata=oy9m
T%2Bl69H%2BmpzM9T2kPXQNSMm5w%2FowLhzziUJX2gZc%3D&reserv
ed=0

Yes, for generating a 1-PPS output waveform, users call ioctl
PTP_CLK_REQ_PEROUT with ptp_perout_request.period={1,0}.

If your device can't control the start time, then it can accept an
unspecified time of ptp_perout_request.start={0,0}.

Get it. Thanks a lot.

quoted

Vladimir talked with me, for the special PPS case, we may consider,
if (req.perout.period.sec ==1 && req.perout.period.nsec == 0) and configure

WAVEFORM_LOW to be equal to req_perout.start.nsec.

quoted

Richard, do you think is it ok?

Sound okay to me (but I don't know about WAVEFORM_LOW).

Sorry. I should have explain more. There is a SYNC bit in Ocelot PTP hardware for PPS generation.
WAFEFORM_LOW register could be used to adjust phase.

RM says,
"For the CLOCK action, the sync option makes the pin generate a single pulse, <WAFEFORM_LOW>
nanoseconds after the time of day has increased the seconds. The pulse will get a width of
<WAVEFORM_HIGH> nanoseconds."

Then I will add PPS case in next version patch.
Thanks.

quoted

And another problem I am facing is, in .enable() callback

(PTP_CLK_REQ_PEROUT request) I defined.

quoted

                /*
                 * TODO: support disabling function
                 * When ptp_disable_pinfunc() is to disable function,
                 * it has already held pincfg_mux.
                 * However ptp_find_pin() in .enable() called also needs
                 * to hold pincfg_mux.
                 * This causes dead lock. So, just return for function
                 * disabling, and this needs fix-up.
                 */
Hope some suggestions here.

See my reply to the patch.

Thanks,
Richard