Hi Marc,
> Il 03/03/2021 10:00 Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> ha scritto:
>
>
> On 03.03.2021 09:23:13, Dario Binacchi wrote:
> [...]
> > > > @@ -1205,17 +1203,31 @@ static int c_can_close(struct net_device *dev)
> > > > return 0;
> > > > }
> > > >
> > > > -struct net_device *alloc_c_can_dev(void)
> > > > +struct net_device *alloc_c_can_dev(int msg_obj_num)
> > > > {
> > > > struct net_device *dev;
> > > > struct c_can_priv *priv;
> > > > + int msg_obj_tx_num = msg_obj_num / 2;
> > >
> > > IMO, a bigger tx queue is not usefull.
> > > A bigger rx queue however is.
> >
> > This would not be good for my application. I think it really depends
> > on the type of application. We can probably say that being able to
> > size rx/tx queue would be a useful feature.
>
> Ok. There is an ethtool interface to configure the size of the RX and TX
> queues. In ethtool it's called the RX/TX "ring" size and you can get it
> via the -g parameter, e.g. here for by Ethernet interface:
>
> | $ ethtool -g enp0s25
> | Ring parameters for enp0s25:
> | Pre-set maximums:
> | RX: 4096
> | RX Mini: n/a
> | RX Jumbo: n/a
> | TX: 4096
> | Current hardware settings:
> | RX: 256
> | RX Mini: n/a
> | RX Jumbo: n/a
> | TX: 256
>
> If I understand correctly patch 6 has some assumptions that RX and TX
> are max 32. To support up to 64 RX objects, you have to convert:
> - u32 -> u64
> - BIT() -> BIT_ULL()
> - GENMASK() -> GENMASK_ULL()
>
> The register access has to be converted, too. For performance reasons
> you want to do as least as possible. Which is probably the most
> complicated.
>
> In the flexcan driver I have a similar problem. The driver keeps masks,
> which mailboxes are RX and which TX and I added wrapper functions to
> minimize IO access:
>
> https://elixir.bootlin.com/linux/v5.11/source/drivers/net/can/flexcan.c#L904
>
> This should to IMHO into patch 6.
>
> Adding the ethtool support and making the rings configurable would be a
> separate patch.
>
I think these features need to be developed in a later series.
I would stay with the extension to 64 messages equally divided
between reception and transmission.
Thanks and regards,
Dario
> regards,
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
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