Re: [PATCH wpan-next 01/20] net: mac802154: Allow the creation of coordinator interfaces

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Alexander Aring <aahringo@redhat.com>
Cc: Alexander Aring <alex.aring@gmail.com>,
	Stefan Schmidt <stefan@datenfreihafen.org>,
	linux-wpan - ML <linux-wpan@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	Network Development <netdev@vger.kernel.org>,
	David Girault <david.girault@qorvo.com>,
	Romuald Despres <romuald.despres@qorvo.com>,
	Frederic Blain <frederic.blain@qorvo.com>,
	Nicolas Schodet <nico@ni.fr.eu.org>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	werner@almesberger.net
Subject: Re: [PATCH wpan-next 01/20] net: mac802154: Allow the creation of coordinator interfaces
Date: Mon, 5 Sep 2022 05:16:08 +0200	[thread overview]
Message-ID: <20220905051608.5354637a@xps-13> (raw)
In-Reply-To: <CAK-6q+jiDcf_M6S+gWh_qms=dMPaSb4daPC7Afs6RZjQdHGinQ@mail.gmail.com>

Hi Alexander,

aahringo@redhat.com wrote on Sat, 3 Sep 2022 15:40:35 -0400:

> Hi,
> 
> On Sat, Sep 3, 2022 at 3:10 PM Alexander Aring <aahringo@redhat.com> wrote:
> >
> > On Sat, Sep 3, 2022 at 3:07 PM Alexander Aring <aahringo@redhat.com> wrote:  
> > >
> > > Hi,
> > >
> > > On Sat, Sep 3, 2022 at 12:06 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> > > ...  
> > > >
> > > > On the Tx side, when sending eg. an association request or an
> > > > association response, I must expect and wait for an ack. This is
> > > > what I am struggling to do. How can I know that a frame which I just
> > > > transmitted has been acked? Bonus points, how can I do that in such a
> > > > way that it will work with other devices? (hints below)
> > > >  
> > > > > AACK will send a back if a frame with ack request bit was received.
> > > > >  
> > > > > > say in a commit) I have seen no further updates about it so I guess
> > > > > > it's still not available. I don't see any other way to know if a
> > > > > > frame's ack has been received or not reliably.  
> > > > >
> > > > > You implemented it for the at86rf230 driver (the spi one which is what
> > > > > also atusb uses). You implemented the
> > > > >
> > > > > ctx->trac = IEEE802154_NO_ACK;
> > > > >
> > > > > which signals the upper layer that if the ack request bit is set, that
> > > > > there was no ack.
> > > > >
> > > > > But yea, there is a missing feature for atusb yet which requires
> > > > > firmware changes as well.  
> > > >
> > > > :'(  
> > >
> > > There is a sequence handling in tx done on atusb firmware and I think
> > > it should be pretty easy to add a byte for trac status.
> > >
> > > diff --git a/atusb/fw/mac.c b/atusb/fw/mac.c
> > > index 835002c..156bd95 100644
> > > --- a/atusb/fw/mac.c
> > > +++ b/atusb/fw/mac.c
> > > @@ -116,7 +116,7 @@ static void receive_frame(void)
> > >
> > >  static bool handle_irq(void)
> > >  {
> > > -       uint8_t irq;
> > > +       uint8_t irq, data[2];
> > >
> > >         irq = reg_read(REG_IRQ_STATUS);
> > >         if (!(irq & IRQ_TRX_END))
> > > @@ -124,7 +124,15 @@ static bool handle_irq(void)
> > >
> > >         if (txing) {
> > >                 if (eps[1].state == EP_IDLE) {
> > > -                       usb_send(&eps[1], &this_seq, 1, tx_ack_done, NULL);
> > > +                       data[0] = tx_ack_done;
> > > +
> > > +                       spi_begin();
> > > +                       spi_io(REG_TRX_STATE);
> > > +
> > > +                       data[1] = spi_recv();
> > > +                       spi_end();  
> >
> > data[1] = reg_read(REG_TRX_STATE) as seen above for REG_IRQ_STATUS
> > would be better here...
> >  
> 
> after digging the code more, there is another queue case which we
> should handle, also correct using buffer parameter instead of the
> callback parameter which was stupid... However I think the direction
> is clear. Sorry for the spam.

Don't be, your feedback is just super useful.

> diff --git a/atusb/fw/mac.c b/atusb/fw/mac.c
> index 835002c..b52ba1a 100644
> --- a/atusb/fw/mac.c
> +++ b/atusb/fw/mac.c
> @@ -32,7 +32,7 @@ static uint8_t tx_buf[MAX_PSDU];
>  static uint8_t tx_size = 0;
>  static bool txing = 0;
>  static bool queued_tx_ack = 0;
> -static uint8_t next_seq, this_seq, queued_seq;
> +static uint8_t next_seq, this_seq, queued_seq, queued_tx_trac;
> 
> 
>  /* ----- Receive buffer management ----------------------------------------- */
> @@ -57,6 +57,7 @@ static void tx_ack_done(void *user);
>  static void usb_next(void)
>  {
>         const uint8_t *buf;
> +       uint8_t data[2];
> 
>         if (rx_in != rx_out) {
>                 buf = rx_buf[rx_out];
> @@ -65,7 +66,9 @@ static void usb_next(void)
>         }
> 
>         if (queued_tx_ack) {
> -               usb_send(&eps[1], &queued_seq, 1, tx_ack_done, NULL);
> +               data[0] = queued_seq;
> +               data[1] = queued_tx_trac;
> +               usb_send(&eps[1], data, sizeof(data), tx_ack_done, NULL);
>                 queued_tx_ack = 0;
>         }
>  }
> @@ -116,7 +119,7 @@ static void receive_frame(void)
> 
>  static bool handle_irq(void)
>  {
> -       uint8_t irq;
> +       uint8_t irq, data[2];

I don't know why, but defining data on the stack just does not work.
Defining it above with the other static variables is okay. I won't
fight more for "today" but if someone has an explanation I am all hears.

>         irq = reg_read(REG_IRQ_STATUS);
>         if (!(irq & IRQ_TRX_END))
> @@ -124,10 +127,13 @@ static bool handle_irq(void)
> 
>         if (txing) {
>                 if (eps[1].state == EP_IDLE) {
> -                       usb_send(&eps[1], &this_seq, 1, tx_ack_done, NULL);
> +                       data[0] = this_seq;
> +                       data[1] = reg_read(REG_TRX_STATE);
> +                       usb_send(&eps[1], data, sizeof(data),
> tx_ack_done, NULL);
>                 } else {
>                         queued_tx_ack = 1;
>                         queued_seq = this_seq;
> +                       queued_tx_trac = reg_read(REG_TRX_STATE);
>                 }
>                 txing = 0;
>                 return 1;
> 

Thanks,
Miquèl