Re: [PATCH v2 1/3] can: ctucanfd: add HW timestamps to RX and error CAN frames

[Matej Vasilevski <matej.vasilevski@seznam.cz>]

On Tue, Aug 02, 2022 at 12:43:38PM +0900, Vincent Mailhol wrote:
> Hi Matej,
> 
> I just send a series last week which a significant amount of changes
> for CAN timestamping tree-wide:
> https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git/commit/?id=12a18d79dc14c80b358dbd26461614b97f2ea4a6
> 
> I suggest you have a look at this series and harmonize it with the new
> features (e.g. Hardware TX timestamp).

Hi Vincent,

thanks for your review! I saw your patch series, but I've only skimmed
through it. I'll read it fully in the evening.

> > @@ -148,6 +149,27 @@ static void ctucan_write_txt_buf(struct ctucan_priv *priv, enum ctu_can_fd_can_r
> >         priv->write_reg(priv, buf_base + offset, val);
> >  }
> >
> > +static u64 concatenate_two_u32(u32 high, u32 low)
> 
> Might be good to add the "namespace" prefix. I suggest:
> 
> static u64 ctucan_concat_tstamp(u32 high, u32 low)
> 
> Because, so far, the function is to be used exclusively with timestamps.
> 
> Also, I was surprised that no helper functions in include/linux/
> headers already do that. But this is another story.
I agree, it is more specific, thanks for the suggestion.

> > +{
> > +       return ((u64)high << 32) | ((u64)low);
> > +}
> > +
> > +u64 ctucan_read_timestamp_counter(struct ctucan_priv *priv)
> > +{
> > +       u32 ts_low;
> > +       u32 ts_high;
> > +       u32 ts_high2;
> > +
> > +       ts_high = ctucan_read32(priv, CTUCANFD_TIMESTAMP_HIGH);
> > +       ts_low = ctucan_read32(priv, CTUCANFD_TIMESTAMP_LOW);
> > +       ts_high2 = ctucan_read32(priv, CTUCANFD_TIMESTAMP_HIGH);
> > +
> > +       if (ts_high2 != ts_high)
> > +               ts_low = priv->read_reg(priv, CTUCANFD_TIMESTAMP_LOW);
> > +
> > +       return concatenate_two_u32(ts_high2, ts_low) & priv->cc.mask;
> > +}
> > +
> >  #define CTU_CAN_FD_TXTNF(priv) (!!FIELD_GET(REG_STATUS_TXNF, ctucan_read32(priv, CTUCANFD_STATUS)))
> >  #define CTU_CAN_FD_ENABLED(priv) (!!FIELD_GET(REG_MODE_ENA, ctucan_read32(priv, CTUCANFD_MODE)))
> 
> 
> #define CTU_CAN_FD_TXTNF(priv) \
>         (!!FIELD_GET(REG_STATUS_TXNF, ctucan_read32(priv, CTUCANFD_STATUS)))
> 
> #define CTU_CAN_FD_ENABLED(priv) \
>         (!!FIELD_GET(REG_MODE_ENA, ctucan_read32(priv, CTUCANFD_MODE)))
> 
> Even if the rule is now more relaxed, the soft limit remains 80
> characters per line:
> 
> https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings
Not from my patch but no problem, I'll fix it in the next version.
Thanks for spotting this.

> > @@ -1295,15 +1341,117 @@ static int ctucan_get_berr_counter(const struct net_device *ndev, struct can_ber
> >         return 0;
> >  }
> >
> > +static int ctucan_hwtstamp_set(struct net_device *dev, struct ifreq *ifr)
> > +{
> > +       struct ctucan_priv *priv = netdev_priv(dev);
> > +       struct hwtstamp_config cfg;
> > +
> > +       if (!priv->timestamp_possible)
> > +               return -EOPNOTSUPP;
> > +
> > +       if (copy_from_user(&cfg, ifr->ifr_data, sizeof(cfg)))
> > +               return -EFAULT;
> > +
> > +       if (cfg.flags)
> > +               return -EINVAL;
> > +
> > +       if (cfg.tx_type != HWTSTAMP_TX_OFF)
> > +               return -ERANGE;
> 
> I have a great news: your driver now also support hardware TX timestamps:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git/commit/?id=8bdd1112edcd3edce2843e03826204a84a61042d
Yes, I'll read your patch series and update accordingly.

> > +
> > +       switch (cfg.rx_filter) {
> > +       case HWTSTAMP_FILTER_NONE:
> > +               priv->timestamp_enabled = false;
> > +               break;
> > +       case HWTSTAMP_FILTER_ALL:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V1_L4_EVENT:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V1_L4_SYNC:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_L4_EVENT:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_L2_EVENT:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_L2_SYNC:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_EVENT:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_SYNC:
> > +               fallthrough;
> > +       case HWTSTAMP_FILTER_PTP_V2_DELAY_REQ:
> > +               priv->timestamp_enabled = true;
> > +               cfg.rx_filter = HWTSTAMP_FILTER_ALL;
> > +               break;
> 
> All those HWTSTAMP_FILTER_PTP_V2_* filters are for UDP, Ethernet or AS1:
> https://elixir.bootlin.com/linux/v5.4.5/source/include/uapi/linux/net_tstamp.h#L106
> 
> Because those layers do not exist in CAN, I suggest treating them all
> as not supported.
> 
> Please have a look at this patch:
> https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git/commit/?id=90f942c5a6d775bad1be33ba214755314105da4a

I followed the Doc/networking/timestamping.txt, and section 3.1 says
"Drivers are free to use a more permissive configuration than the requested
configuration."
So I've added in all the _PTP filters etc. If the consensus is that
_NONE and _ALL filters are enough, I'll gladly remove the dozen of
unnecessary cases.


> > +       default:
> > +               return -ERANGE;
> > +       }
> > +
> > +       return copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)) ? -EFAULT : 0;
> > +}
> > +
> > +static int ctucan_hwtstamp_get(struct net_device *dev, struct ifreq *ifr)
> > +{
> > +       struct ctucan_priv *priv = netdev_priv(dev);
> > +       struct hwtstamp_config cfg;
> > +
> > +       if (!priv->timestamp_possible)
> > +               return -EOPNOTSUPP;
> > +
> > +       cfg.flags = 0;
> > +       cfg.tx_type = HWTSTAMP_TX_OFF;
> 
> Hardware TX timestamps are now supported (c.f. supra).
ACK
> 
> > +       cfg.rx_filter = priv->timestamp_enabled ? HWTSTAMP_FILTER_ALL : HWTSTAMP_FILTER_NONE;
> > +       return copy_to_user(ifr->ifr_data, &cfg, sizeof(cfg)) ? -EFAULT : 0;
> > +}
> > +
> > +static int ctucan_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
> 
> Please consider using the generic function can_eth_ioctl_hwts()
> https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git/commit/?id=90f942c5a6d775bad1be33ba214755314105da4a
I've seen it, but I have to use a custom ioctl function, if I want to
toggle rx timestamps enabled/disabled.
> > +{
> > +       switch (cmd) {
> > +       case SIOCSHWTSTAMP:
> > +               return ctucan_hwtstamp_set(dev, ifr);
> > +       case SIOCGHWTSTAMP:
> > +               return ctucan_hwtstamp_get(dev, ifr);
> > +       default:
> > +               return -EOPNOTSUPP;
> > +       }
> > +}
> >
> > +static int ctucan_ethtool_get_ts_info(struct net_device *ndev, struct ethtool_ts_info *info)
> 
> Please break the line to meet the 80 columns soft limit.
> 
> Please consider using the generic function can_ethtool_op_get_ts_info_hwts():
> https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git/commit/?id=7fb48d25b5ce3bc488dbb019bf1736248181de9a
> 
> Something like that:
> static int ctucan_ethtool_get_ts_info(struct net_device *ndev,
>                                       struct ethtool_ts_info *inf
> {
>         struct ctucan_priv *priv = netdev_priv(ndev);
> 
>         if (!priv->timestamp_possible)
>                 ethtool_op_get_ts_info(ndev, info);
> 
>         return can_ethtool_op_get_ts_info_hwts(ndev, info);
> }
Sure, this is better, I'll include it in v3. Thank you.
> > +{
> > +       struct ctucan_priv *priv = netdev_priv(ndev);
> > +
> > +       ethtool_op_get_ts_info(ndev, info);
> > +
> > +       if (!priv->timestamp_possible)
> > +               return 0;
> > +
> > +       info->so_timestamping |= SOF_TIMESTAMPING_RX_HARDWARE |
> > +                                SOF_TIMESTAMPING_RAW_HARDWARE;
> > +       info->tx_types = BIT(HWTSTAMP_TX_OFF);
> 
> Hardware TX timestamps are now supported (c.f. supra).
ACK
> > +       info->rx_filters = BIT(HWTSTAMP_FILTER_NONE) |
> > +                          BIT(HWTSTAMP_FILTER_ALL);
> > +
> > +       return 0;
> > +}
> > +
> > @@ -1386,7 +1536,9 @@ int ctucan_probe_common(struct device *dev, void __iomem *addr, int irq, unsigne
> >
> >         /* Getting the can_clk info */
> >         if (!can_clk_rate) {
> > -               priv->can_clk = devm_clk_get(dev, NULL);
> > +               priv->can_clk = devm_clk_get_optional(dev, "core-clk");
> > +               if (!priv->can_clk)
> > +                       priv->can_clk = devm_clk_get(dev, NULL);
> >                 if (IS_ERR(priv->can_clk)) {
> >                         dev_err(dev, "Device clock not found.\n");
> 
> Just a suggestion, but you may want to print the mnemotechnic of the error code:
> dev_err(dev, "Device clock not found: %pe.\n", priv->can_clk);
Yes the error print might need some tweaking, I'll think about it.

> >                         ret = PTR_ERR(priv->can_clk);
> > @@ -1425,6 +1577,54 @@ int ctucan_probe_common(struct device *dev, void __iomem *addr, int irq, unsigne
> >
> >         priv->can.clock.freq = can_clk_rate;