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

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Date:	Mon, 16 Mar 2015 08:16:36 -0400
From:	"Ahmed S. Darwish" <darwish.07@...il.com>
To:	Marc Kleine-Budde <mkl@...gutronix.de>
Cc:	Olivier Sobrie <olivier@...rie.be>,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Wolfgang Grandegger <wg@...ndegger.com>,
	Andri Yngvason <andri.yngvason@...el.com>,
	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 Sun, Mar 15, 2015 at 07:08:23PM +0100, Marc Kleine-Budde wrote:
> 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.
> 

Sure, go ahead.

I have my reasons for that hunk above, but we can always discuss
this in another separate patch ;-)

Thanks,
Darwish
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