netdev - Re: [PATCH v5 09/11] net: ieee802154: atusb: Call _xmit

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Date:   Mon, 25 Apr 2022 08:35:55 -0400
From:   Alexander Aring <alex.aring@...il.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Stefan Schmidt <stefan@...enfreihafen.org>,
        linux-wpan - ML <linux-wpan@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        David Girault <david.girault@...vo.com>,
        Romuald Despres <romuald.despres@...vo.com>,
        Frederic Blain <frederic.blain@...vo.com>,
        Nicolas Schodet <nico@...fr.eu.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v5 09/11] net: ieee802154: atusb: Call _xmit_error() when
 a transmission fails

Hi,

On Thu, Apr 7, 2022 at 4:06 AM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
>
> Hi Alexander,
>
> alex.aring@...il.com wrote on Wed, 6 Apr 2022 17:58:59 -0400:
>
> > Hi,
> >
> > On Wed, Apr 6, 2022 at 11:34 AM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
> > >
> > > ieee802154_xmit_error() is the right helper to call when a transmission
> > > has failed. Let's use it instead of open-coding it.
> > >
> > > Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
> > > ---
> > >  drivers/net/ieee802154/atusb.c | 5 ++---
> > >  1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/net/ieee802154/atusb.c b/drivers/net/ieee802154/atusb.c
> > > index f27a5f535808..d04db4d07a64 100644
> > > --- a/drivers/net/ieee802154/atusb.c
> > > +++ b/drivers/net/ieee802154/atusb.c
> > > @@ -271,9 +271,8 @@ static void atusb_tx_done(struct atusb *atusb, u8 seq)
> > >                  * unlikely case now that seq == expect is then true, but can
> > >                  * happen and fail with a tx_skb = NULL;
> > >                  */
> > > -               ieee802154_wake_queue(atusb->hw);
> > > -               if (atusb->tx_skb)
> > > -                       dev_kfree_skb_irq(atusb->tx_skb);
> > > +               ieee802154_xmit_error(atusb->hw, atusb->tx_skb,
> > > +                                     IEEE802154_SYSTEM_ERROR);
> >
> > That should then call the xmit_error for ANY other reason which is not
> > 802.15.4 specific which is the bus_error() function?
>
> I'll drop the bus error function so we can stick to a regular
> _xmit_error() call.
>

Okay, this error is only hardware related.

> Besides, we do not have any trac information nor any easy access to
> what failed exactly, so it's probably best anyway.

This is correct, Somebody needs to write support for it for atusb firmware. [0]
However some transceivers can't yet or will never (because lack of
functionality?) report such errors back... they will act a little bit
weird.

However, this return value is a BIG step moving into the right
direction that other drivers can follow.

I think for MLME ops we can definitely handle some transmit errors now
and retry so that we don't wait for anything when we know the
transceiver was never submitting.

- Alex

[0] http://projects.qi-hardware.com/index.php/p/ben-wpan/source/tree/master/atusb/fw