netdev - Re: [RFC PATCH] can: flexcan: add ethtool support to get rx/tx ring parameters

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Date:   Sun, 9 Jan 2022 12:22:54 +0100
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC PATCH] can: flexcan: add ethtool support to get rx/tx ring parameters

On Sat, Jan 8, 2022 at 9:16 PM Marc Kleine-Budde <mkl@...gutronix.de> wrote:
>
> On 08.01.2022 19:16:33, Dario Binacchi wrote:
> > Adds ethtool support to get the number of message buffers configured for
> > reception/transmission, which may also depends on runtime configurations
> > such as the 'rx-rtr' flag state.
> >
> > Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
> >
> > ---
> >
> >  drivers/net/can/flexcan/flexcan-ethtool.c | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> >
> > diff --git a/drivers/net/can/flexcan/flexcan-ethtool.c b/drivers/net/can/flexcan/flexcan-ethtool.c
> > index 5bb45653e1ac..d119bca584f6 100644
> > --- a/drivers/net/can/flexcan/flexcan-ethtool.c
> > +++ b/drivers/net/can/flexcan/flexcan-ethtool.c
> > @@ -80,7 +80,24 @@ static int flexcan_set_priv_flags(struct net_device *ndev, u32 priv_flags)
> >       return 0;
> >  }
> >
> > +static void flexcan_get_ringparam(struct net_device *ndev,
> > +                               struct ethtool_ringparam *ring)
>
> This doesn't compile on net-next/master, as the prototype of the
> get_ringparam callback changed, fixed this while applying.
>
> > +{
> > +     struct flexcan_priv *priv = netdev_priv(ndev);
> > +
> > +     ring->rx_max_pending = priv->mb_count;
> > +     ring->tx_max_pending = priv->mb_count;
> > +
> > +     if (priv->devtype_data.quirks & FLEXCAN_QUIRK_USE_RX_MAILBOX)
> > +             ring->rx_pending = __sw_hweight64(priv->rx_mask);
>
> I've replaced the hamming weight calculation by the simpler:
>
> |               ring->rx_pending = priv->offload.mb_last -
> |                       priv->offload.mb_first + 1;
>
> > +     else
> > +             ring->rx_pending = 6;
> > +
> > +     ring->tx_pending = __sw_hweight64(priv->tx_mask);
>
> ...and here I added a hardcoded "1", as the driver currently only
> support on TX buffer.
>
> > +}
> > +
> >  static const struct ethtool_ops flexcan_ethtool_ops = {
> > +     .get_ringparam = flexcan_get_ringparam,
> >       .get_sset_count = flexcan_get_sset_count,
> >       .get_strings = flexcan_get_strings,
> >       .get_priv_flags = flexcan_get_priv_flags,
>
> BTW: If you're looking for more TX performance, this can be done by
> using more than one TX buffer.

I didn't expect only one message buffer to be used for transmission

thanks and regards,
Dario

> It's also possible to configure the
> number of RX and TX buffers via ethtool during runtime. I'm currently
> preparing a patch set for the mcp251xfd to implement this.
>
> regards,
> Marc
>
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
> Embedded Linux                   | https://www.pengutronix.de  |
> Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |



-- 

Dario Binacchi

Embedded Linux Developer

dario.binacchi@...rulasolutions.com

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