netdev - Re: [PATCH net-next v2] net: mvpp2: tai: warn once if we fail to update our timestamp

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Message-ID: <Z1l9YFEbAfR3SBff@shell.armlinux.org.uk>
Date: Wed, 11 Dec 2024 11:54:08 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Mateusz Polchlopek <mateusz.polchlopek@...el.com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Marcin Wojtas <marcin.s.wojtas@...il.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Richard Cochran <richardcochran@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2] net: mvpp2: tai: warn once if we fail to
 update our timestamp

On Wed, Dec 11, 2024 at 12:48:21PM +0100, Mateusz Polchlopek wrote:
> On 12/11/2024 11:55 AM, Russell King wrote:
> > The hardware timestamps for packets contain a truncated seconds field,
> > only containing two bits of seconds. In order to provide the full
> > number of seconds, we need to keep track of the full hardware clock by
> > reading it every two seconds.
> > 
> > However, if we fail to read the clock, we silently ignore the error.
> > Print a warning indicating that the PP2 TAI clock timestamps have
> > become unreliable.
> > 
> > Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
> > --
> > v2: correct dev_warn_once() indentation
> > ---
> >   drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
> > index 95862aff49f1..6b60beb1f3ed 100644
> > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
> > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
> > @@ -54,6 +54,7 @@
> >   #define TCSR_CAPTURE_0_VALID		BIT(0)
> >   struct mvpp2_tai {
> > +	struct device *dev;
> >   	struct ptp_clock_info caps;
> >   	struct ptp_clock *ptp_clock;
> >   	void __iomem *base;
> > @@ -303,7 +304,8 @@ static long mvpp22_tai_aux_work(struct ptp_clock_info *ptp)
> >   {
> >   	struct mvpp2_tai *tai = ptp_to_tai(ptp);
> > -	mvpp22_tai_gettimex64(ptp, &tai->stamp, NULL);
> > +	if (mvpp22_tai_gettimex64(ptp, &tai->stamp, NULL) < 0)
> > +		dev_warn_once(tai->dev, "PTP timestamps are unreliable");
> 
> Only small nitpick/question - shouldn't text end with '\n'? I see in the
> code that most of calls of dev_warn_once has '\n' at the end.

Yes, thanks for spotting.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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