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

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Date:	Sun, 15 Mar 2015 19:08:23 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	"Ahmed S. Darwish" <darwish.07@...il.com>,
	Olivier Sobrie <olivier@...rie.be>,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Wolfgang Grandegger <wg@...ndegger.com>,
	Andri Yngvason <andri.yngvason@...el.com>
CC:	Linux-CAN <linux-can@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/2] can: kvaser_usb: Comply with firmware max
 tx URBs value

On 03/15/2015 04:03 PM, Ahmed S. Darwish wrote:
> From: Ahmed S. Darwish <ahmed.darwish@...eo.com>
> 
> 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@...eo.com>

> @@ -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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