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Date:   Fri, 13 Oct 2023 19:14:46 +0300
From:   Vladimir Oltean <vladimir.oltean@nxp.com>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     =?utf-8?B?S8O2cnk=?= Maincent <kory.maincent@bootlin.com>,
        Florian Fainelli <florian.fainelli@broadcom.com>,
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Subject: Re: [PATCH net-next v5 08/16] net: ethtool: Add a command to expose
 current time stamping layer
Message-ID: <20231013161446.st7tlemyaj3ggkgk@skbuf>
References: <20231009155138.86458-1-kory.maincent@bootlin.com>
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On Fri, Oct 13, 2023 at 09:00:20AM -0700, Jakub Kicinski wrote:
> On Tue, 10 Oct 2023 10:23:43 +0200 K?ry Maincent wrote:
> > > Why do we have to set NETDEV_TIMESTAMPING here, or is this a round-about 
> > > way of enumerating 0, 1, 2 and 3?  
> > 
> > I answered you above the software timestamping should have the
> > NETDEV_TIMESTAMPING bit set as it is done from the net device driver.
> > 
> > What I was thinking is that all the new timestamping should have
> > NETDEV_TIMESTAMPING or PHYLIB_TIMESTAMPING set to know which API to pass
> > through.
> > Like we could add these in the future:
> > MAC_DMA_TIMESTAMPING = (2 << 2) | (1 >> 0),
> > MAC_PRECISION_TIMESTAMPING = (3 << 2) | (1 >> 0),
> > ...
> > PHY_SFP_TIMESTAMPING = (2 << 2) | (1 << 1),
> > ...
> 
> What is "PRECISION"? DMA is a separate block like MAC and PHY.

If DMA is a separate block like MAC and PHY, can it have its own PHC
device, and the ethtool UAPI only lists the timestamping-capable PHCs
for one NIC, and is able to select between them? Translation between the
UAPI-visible PHC index and MAC, DMA, phylib PHY, other PHY etc can then
be done by the kernel as needed.