Re: [PATCH v5 1/2] can: kvaser_usb: Comply with firmware max tx URBs value

From: Marc Kleine-Budde
Date: Sun Mar 15 2015 - 14:29:37 EST


On 03/15/2015 04:03 PM, Ahmed S. Darwish wrote:
> From: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx>
>
> Current driver code arbitrarily assumes a max outstanding tx
> value of 16 parallel transmissions. Meanwhile, the device
> firmware provides its actual maximum inside its reply to the
> CMD_GET_SOFTWARE_INFO message.
>
> Under heavy tx traffic, if the interleaved transmissions count
> increases above the limit reported by firmware, the firmware
> breaks up badly, reports a massive list of internal errors, and
> the candump traces hardly matches the actual frames sent and
> received.
>
> On the other hand, in certain models, the firmware can support
> up to 48 tx URBs instead of just 16, increasing the driver
> throughput by two-fold and reducing the possibility of -ENOBUFs.
>
> Thus dynamically set the driver's max tx URBs value according
> to firmware replies.
>
> Signed-off-by: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx>

> @@ -1928,7 +1940,7 @@ static int kvaser_usb_init_one(struct usb_interface *intf,
> return err;
> }
>
> - netdev_dbg(netdev, "device registered\n");
> + netdev_info(netdev, "device registered\n");

This makes the driver more noisy, I'd like to drop that hunk, okay? No
need to resend.

regards,
Marc

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