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Date:   Tue, 24 Mar 2020 10:24:36 +0100
From:   Horatiu Vultur <horatiu.vultur@microchip.com>
To:     Vladimir Oltean <olteanv@gmail.com>
CC:     Yangbo Lu <yangbo.lu@nxp.com>, lkml <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        "David S . Miller" <davem@davemloft.net>,
        "Richard Cochran" <richardcochran@gmail.com>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        Claudiu Manoil <claudiu.manoil@nxp.com>,
        "Andrew Lunn" <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        "Florian Fainelli" <f.fainelli@gmail.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
Subject: Re: [PATCH 6/6] ptp_ocelot: support 4 programmable pins
Message-ID: <20200324092436.stq25qac2h4rm3il@soft-dev3.microsemi.net>
References: <20200320103726.32559-1-yangbo.lu@nxp.com>
 <20200320103726.32559-7-yangbo.lu@nxp.com>
 <CA+h21hoBwDuWCFbO70u1FAERB8zc5F+H5URBkn=2_bpRRRz1oA@mail.gmail.com>
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Hi Vladimir,

The 03/20/2020 15:20, Vladimir Oltean wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Hi Yangbo,
> 
> On Fri, 20 Mar 2020 at 12:42, Yangbo Lu <yangbo.lu@nxp.com> wrote:
> >
> > Support 4 programmable pins for only one function periodic
> > signal for now. Since the hardware is not able to support
> > absolute start time, driver starts periodic signal immediately.
> >
> 
> Are you absolutely sure it doesn't support absolute start time?
> Because that would mean it's pretty useless if the phase of the PTP
> clock signal is out of control.

It looks like there is no support for absolute start time. But you
should be able to control the phase using the register
PIN_WF_LOW_PERIOD.

> 
> I tested your patch on the LS1028A-RDB board using the following commands:
> 
> # Select PEROUT function and assign a channel to each of pins
> SWITCH_1588_DAT0 and SWITCH_1588_DAT1
> echo '2 0' > /sys/class/ptp/ptp1/pins/switch_1588_dat0
> echo '2 1' > /sys/class/ptp/ptp1/pins/switch_1588_dat1
> # Generate pulses with 1 second period on channel 0
> echo '0 0 0 1 0' > /sys/class/ptp/ptp1/period
> # Generate pulses with 1 second period on channel 1
> echo '1 0 0 1 0' > /sys/class/ptp/ptp1/period
> 
> And here is what I get:
> https://drive.google.com/open?id=1ErWufJL0TWv6hKDQdF1pRL5gn4hn4X-r
> 
> So the periodic output really starts 'now' just like the print says,
> so the output from DAT0 is not even in sync with DAT1.
> 
> > Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
> > ---
> 
> Thanks,
> -Vladimir

-- 
/Horatiu