From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: Re: usb-can device Date: Tue, 28 Aug 2012 14:20:06 +0200 Message-ID: <503CB776.8030303@pengutronix.de> References: <1345996339.6610.10.camel@slaptop> <503A4E9B.9060308@pengutronix.de> <503B1198.3010506@hartkopp.net> <1346071259.3928.33.camel@slaptop> <503CB26E.7010106@hartkopp.net> <503CB5DF.4030707@pengutronix.de> <503CB70A.8040506@hartkopp.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigA1629B1F13303697F23459FC" Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:52604 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751366Ab2H1MUN (ORCPT ); Tue, 28 Aug 2012 08:20:13 -0400 In-Reply-To: <503CB70A.8040506@hartkopp.net> Sender: linux-can-owner@vger.kernel.org List-ID: To: Oliver Hartkopp Cc: "Max S." , "linux-can@vger.kernel.org" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigA1629B1F13303697F23459FC Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 08/28/2012 02:18 PM, Oliver Hartkopp wrote: [...] >>> I found a very interesting implementation in the Bosch M_CAN specific= ation: >>> >>> http://www.semiconductors.bosch.de/en/ipmodules/can/canipmodules/m_ca= n/m_can.asp >>> >>> http://www.semiconductors.bosch.de/media/en/pdf/ipmodules_1/m_can/mca= n_users_manual.pdf >>> >>> Section 2.4.3 Tx Buffer Element (page 45) >>> >>> ---8<--- >>> >>> T1 Bits 31:24 MM[7:0]: Message Marker >>> >>> Written by CPU during Tx Buffer configuration. Copied into Tx Event F= IFO >>> element for identification of Tx message status. >>> >>> ---8<--- >>> >>> So you can see in the Tx event FIFO, which marked CAN frame has been = sent. >>> >>> This is probably enough to provide just a byte and to create an array= of >>> skb pointers which is referenced by this Message Marker. Maybe 256 ma= rkers >>> are too much ... we could only use 8 markers IMO. >> >> Why not a full u32? Then you're free on the driver side to do what you= >> want with it. >=20 >=20 > Yes. You're right. It's a marker - and if i personally only want to han= dle an > index into an array with 8 elements with my driver it's my choice. ACK :) Marc --=20 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 | --------------enigA1629B1F13303697F23459FC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://www.enigmail.net/ iEYEARECAAYFAlA8t3kACgkQjTAFq1RaXHNsTACbBSKim1ZjuKs6RxYaGMtrZ0j+ 4D0AniZDPhzI3kQzuDdHq1ZzeauJc/rv =rZe5 -----END PGP SIGNATURE----- --------------enigA1629B1F13303697F23459FC--