netdev - Re: [PATCH v2 net-next 9/9] lan743x: Add PTP support

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Date:   Wed, 18 Jul 2018 13:55:54 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Bryan.Whitehead@...rochip.com
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v2 net-next 9/9] lan743x: Add PTP support

On Wed, Jul 18, 2018 at 08:04:08PM +0000, Bryan.Whitehead@...rochip.com wrote:
> Thank you for your detailed feedback. I'm working on it now, but I feel it will take a little extra time to complete. Therefor I'm planning to remove PTP support from this patch series, and resubmit it in a new patch later.

Ok.

> > > +	if (cleanup) {
> > > +		lan743x_ptp_unrequest_tx_timestamp(tx->adapter);
> > > +		dev_kfree_skb(buffer_info->skb);
> > > +	} else {
> > > +		lan743x_ptp_tx_timestamp_skb(tx->adapter,
> > > +					     buffer_info->skb,
> > > +					     (buffer_info->flags &
> > > +
> > TX_BUFFER_INFO_FLAG_IGNORE_SYNC)
> > > +					     != 0);
> > 
> > This is poor coding style.  Please find a better way.
> 
> Can you clarify what is poor and what would be better?
> For example, should I change "X != 0" to "X ? true : false".

Look at this:
		lan743x_ptp_tx_timestamp_skb(tx->adapter,
					     buffer_info->skb,
					     (buffer_info->flags &
					     TX_BUFFER_INFO_FLAG_IGNORE_SYNC)
					     != 0);

Can't you reduce

	(buffer_info->flags & TX_BUFFER_INFO_FLAG_IGNORE_SYNC) != 0

into a local variable:

		lan743x_ptp_tx_timestamp_skb(tx->adapter, buffer_info->skb, xyz);
?

> So you mean PPS is not intended to generate a physical signal?

Yes.

> It is only intended to call ptp_clock_event?

Yes.

> I can configure the hardware to generate an interrupt each second and then call 
> ptp_clock_event. Would that satisfy the pps requirements?

Yes.
 
> Regarding PTP_CLK_REQ_PEROUT. Is that intended for physical signals?

Yes.

Thanks,
Richard