netdev - RE: [PATCH 3/3] net/mlx4_en: Add HW timestamping (TS) support

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Date:	Fri, 28 Sep 2012 14:10:33 +0000
From:	Yevgeny Petrilin <yevgenyp@...lanox.com>
To:	Richard Cochran <richardcochran@...il.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Eugenia Emantayev <eugenia@...lanox.com>
Subject: RE: [PATCH 3/3] net/mlx4_en: Add HW timestamping (TS) support

> > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > index edd9cb8..10fa453 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > @@ -1517,6 +1517,60 @@ static int mlx4_en_change_mtu(struct net_device
> *dev, int new_mtu)
> >  	return 0;
> >  }
> >
> > +static int mlx4_en_hwtstamp_ioctl(struct net_device *dev, struct ifreq *ifr)
> > +{
> > +	struct mlx4_en_priv *priv = netdev_priv(dev);
> > +	struct mlx4_en_dev *mdev = priv->mdev;
> > +	struct hwtstamp_config config;
> > +
> > +	if (copy_from_user(&config, ifr->ifr_data, sizeof(config)))
> > +		return -EFAULT;
> > +
> > +	/* reserved for future extensions */
> > +	if (config.flags)
> > +		return -EINVAL;
> > +
> > +	/* device doesn't support time stamping */
> > +	if (!(mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_TS_EN))
> > +		return -EINVAL;
> > +
> > +	/* TX HW timestamp */
> > +	switch (config.tx_type) {
> > +	case HWTSTAMP_TX_OFF:
> > +	case HWTSTAMP_TX_ON:
> > +		break;
> > +	default:
> > +		return -ERANGE;
> > +	}
> > +
> > +	/* RX HW timestamp */
> > +	switch (config.rx_filter) {
> > +	case HWTSTAMP_FILTER_NONE:
> > +	case HWTSTAMP_FILTER_ALL:
> > +		break;
> > +	default:
> 
> Instead of rejecting the HWTSTAMP_FILTER_PTP_ codes out of hand, you
> should just accept them, and return by promoting rx_filter to
> HWTSTAMP_FILTER_ALL.
> 
> [ See Documentation/networking/timestamping.txt ]
> 
> > +		return -ERANGE;
> > +	}
> > +
> > +	if (mlx4_en_timestamp_config(dev, config.tx_type, config.rx_filter)) {
> > +		config.tx_type = HWTSTAMP_TX_OFF;
> > +		config.rx_filter = HWTSTAMP_FILTER_NONE;
> > +	}
> > +
> > +	return copy_to_user(ifr->ifr_data, &config,
> > +			    sizeof(config)) ? -EFAULT : 0;
> > +}
> 
> ...
> 
> > @@ -363,6 +368,9 @@ struct mlx4_en_dev {
> >  	u32                     priv_pdn;
> >  	spinlock_t              uar_lock;
> >  	u8			mac_removed[MLX4_MAX_PORTS + 1];
> > +	struct cyclecounter	cycles;
> > +	struct timecounter	clock;
> > +	struct timecompare	compare;
> 
> I am working on a patch to remove the timecompare stuff altogether
> (after removing it from blackfin). It is and was a bad idea, I would
> hate to see new drivers using it.
> 
> I strongly recommend just offering raw hardware time stamps in
> nanosecond resolution. Also, why not expose your device as a PTP
> Hardware Clock?
> 
> Thanks,
> Richard

Hello Richard,
Thanks for your feedback,
Will address all your comments in V1 of this patchset.

Thanks,
Yevgeny 
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