netdev - Re: [PATCH 2/3] net: uapi: Add HWTSTAMP_FLAGS_ADJ_FINE/ADJ

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Date:   Thu, 14 May 2020 17:20:41 +0200
From:   Olivier Dautricourt <olivier.dautricourt@...lia.com>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH 2/3] net: uapi: Add HWTSTAMP_FLAGS_ADJ_FINE/ADJ_COARSE

The 05/14/2020 06:38, Richard Cochran wrote:
> On Thu, May 14, 2020 at 12:28:07PM +0200, Olivier Dautricourt wrote:
> > This commit allows a user to specify a flag value for configuring
> > timestamping through hwtsamp_config structure.
> >
> > New flags introduced:
> >
> > HWTSTAMP_FLAGS_NONE = 0
> >       No flag specified: as it is of value 0, this will selects the
> >       default behavior for all the existing drivers and should not
> >       break existing userland programs.
> >
> > HWTSTAMP_FLAGS_ADJ_FINE = 1
> >       Use the fine adjustment mode.
> >       Fine adjustment mode is usually used for precise frequency adjustments.
> >
> > HWTSTAMP_FLAGS_ADJ_COARSE = 2
> >       Use the coarse adjustment mode
> >       Coarse adjustment mode is usually used for direct phase correction.
> 
> I'll have to NAK this change.  The purpose of HWTSTAMP ioctl is to
> configure the hardware time stamp settings.  This patch would misuse
> it for some other purpose.

Hello,
 
Can't we consider this as a time stamp settings ?
I don't see where we could put those driver-specific flags.
That flag field was reserved for futher improvements so i found
it acceptable to specify that here.

This ioctl structure is used in the driver initialization
function which is reponsible for configuring the mac.
Adding an ioctl for that may be redundant.
But i'd like your opinion on that.

> 
> Sorry,
> Richard


Regards,

-- 
Olivier Dautricourt