Re: [PATCH v2 09/13] can: pruss CAN driver. - Marc Kleine-Budde

From: Marc Kleine-Budde <mkl-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
To: Subhasish Ghosh
	<subhasish-EvXpCiN+lbve9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
Cc: sachi-EvXpCiN+lbve9wHmmfpqLFaTQe2KTcn/@public.gmane.org,
	davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org,
	CAN NETWORK DRIVERS
	<netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	nsekhar-l0cyMroinI0@public.gmane.org,
	open list <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	CAN NETWORK DRIVERS
	<socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org>,
	Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>,
	m-watkins-l0cyMroinI0@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH v2 09/13] can: pruss CAN driver.
Date: Mon, 14 Feb 2011 14:33:17 +0100	[thread overview]
Message-ID: <4D592F1D.8010600@pengutronix.de> (raw)
In-Reply-To: <8CB9F2C8F75C4041B9F0691D209DDAFD@subhasishg>

[-- Attachment #1.1: Type: text/plain, Size: 1296 bytes --]

On 02/14/2011 02:15 PM, Subhasish Ghosh wrote:
> Hello,
> 
> The problem with the "all" implementation is that it hogs the ARM/DSP
> heavily and that's the reason why we specifically avoided this in our
> firmware design.
> Hence, implementing this condition spoils the whole purpose of the PRU!!

What about implementing the standard id/mask approach?

if (canid & mask == id & mask)
	aceept();
else
	discard();

To keep the hot-path as small as possible, the id & mask operation is
done during setup, only one. This is probably just an additional "and"
operation (the "& mask"). This opens the way to act like a normal can
controller.

As long as we don't have any support for hardware filters in socketcan,
it's a good choice to use sysfs to configure your filters.

Have a look at [1] and [2] for how to use sysfs files.

cheers, Marc

[1]
http://git.kernel.org/linus/3a5655a5b545e9647c3437473ee3d815fe1b9050

[2]
http://git.kernel.org/linus/fef52b0171dfd7dd9b85c9cc201bd433b42a8ded

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |

[-- Attachment #1.2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 262 bytes --]

[-- Attachment #2: Type: text/plain, Size: 188 bytes --]

_______________________________________________
Socketcan-core mailing list
Socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org
https://lists.berlios.de/mailman/listinfo/socketcan-core