From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_CAN driver to 2.6.35 Date: Tue, 14 Sep 2010 09:08:48 +0200 Message-ID: <4C8F1F80.5050505@pengutronix.de> References: <4C61EDE5.4030505@dsn.okisemi.com> <4C629FE5.6000204@pengutronix.de> <005f01cb533e$5c21d530$66f8800a@maildom.okisemi.com> <4C8E1918.5000007@pengutronix.de> <003a01cb53a6$4ca724d0$66f8800a@maildom.okisemi.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigB376FB62D7045DD117621BB1" Cc: Wolfgang Grandegger , arjan@linux.intel.com, meego-dev@meego.com, Morinaga , socketcan-core@lists.berlios.de, yong.y.wang@intel.com, gregkh@suse.de, netdev@vger.kernel.org, qi.wang@intel.com, andrew.chih.howe.khor@intel.com To: Masayuki Ohtake Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:60182 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752507Ab0INHJI (ORCPT ); Tue, 14 Sep 2010 03:09:08 -0400 In-Reply-To: <003a01cb53a6$4ca724d0$66f8800a@maildom.okisemi.com> Sender: netdev-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigB376FB62D7045DD117621BB1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 09/14/2010 02:46 AM, Masayuki Ohtake wrote: >>>> - implement NAPI >>> Since Topcliff CAN HW register has only single rx buffer, >>> I think NAPI is unnecessary. >=20 >> Doesn't matter. Please try to implement it. >=20 > Our CAN driver must pull received data from CAN-HW rx buffer as fast as= it can > so that the received data is not over-written by next received data. > In case of implemented with NAPI, > since NAPI has time-lagging after receiving first packet, > probability of over-written(discarded) buffer is to be high. > Thus, for our CAN HW, we should NOT implement with NAPI but normal "net= if_rx". Okay, point taken. Regarding the one and only rx buffer. Is it a driver or a hardware limitation? BTW: Are the datasheets of this CAN core available somewhere? cheers 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 | --------------enigB376FB62D7045DD117621BB1 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://enigmail.mozdev.org/ iEYEARECAAYFAkyPH4UACgkQjTAFq1RaXHODoACeJqeVrDA9Ie942MNE6MHH0XvK qVoAnRDVzC7qIJ6lcZI2hbAlVuLtHdBT =hDvx -----END PGP SIGNATURE----- --------------enigB376FB62D7045DD117621BB1--