From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E5CCC4743C for ; Mon, 21 Jun 2021 12:37:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74F4760FF2 for ; Mon, 21 Jun 2021 12:37:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229651AbhFUMjZ (ORCPT ); Mon, 21 Jun 2021 08:39:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229663AbhFUMjW (ORCPT ); Mon, 21 Jun 2021 08:39:22 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B28E6C061574 for ; Mon, 21 Jun 2021 05:37:07 -0700 (PDT) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=bjornoya.blackshift.org) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lvJAn-00086G-Qq; Mon, 21 Jun 2021 14:37:05 +0200 Received: from pengutronix.de (unknown [IPv6:2a03:f580:87bc:d400:3569:1fb5:40be:61fc]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: mkl-all@blackshift.org) by smtp.blackshift.org (Postfix) with ESMTPSA id B30D8640644; Mon, 21 Jun 2021 12:37:04 +0000 (UTC) Date: Mon, 21 Jun 2021 14:37:04 +0200 From: Marc Kleine-Budde To: Fabio Estevam Cc: linux-can@vger.kernel.org, Oliver Hartkopp , "Paul E . McKenney" Subject: Re: Testing two MCP2518FD's on i.MX8MM Message-ID: <20210621123704.yc7ohwbuedofoq53@pengutronix.de> References: <20210615071557.o7fjkleuk777otvm@pengutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="xn57vvywhbh4vq4z" Content-Disposition: inline In-Reply-To: X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-can@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org --xn57vvywhbh4vq4z Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 21.06.2021 09:24:31, Fabio Estevam wrote: > > The imx SPI driver has quite some overhead, when it comes to small SPI > > transfers. The mcp251fd driver performs much better with the SPI IP > > cores on the raspi, which have quite good optimized drivers. > > > > Hook up a scope to the SPI's clock and chip select lines of the imx, > > you'll see the time between end of transfer until the chip select is > > inactive is longer than the SPI transfer itself. > > > > I expect most bang for the buck can be archived by adding an IRQ less > > busy polling transfer mode, which kicks in below a certain SPI transfer > > length. > > > > On the mcp251xfd driver side, there is some room for optimization. The > > basic idea is to reduce the number of SPI transfers by combining several > > reads into one transfer. This can be done in some places. > > > > For peak loads in CAN-2.0 mode it would be interesting to make use of > > the remaining RAM for a 2nd FIFO. >=20 > Thanks for your reply. >=20 > I do see some RCU related errors every time the application is launched: [...] > Any ideas how these RCU errors could be fixed? Can you test if https://lore.kernel.org/r/20210621123436.2897023-1-mkl@pengutronix.de fixes your problem? We still have to check if lockdep complains... regards, Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | --xn57vvywhbh4vq4z Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEK3kIWJt9yTYMP3ehqclaivrt76kFAmDQh+0ACgkQqclaivrt 76nBzwf/Qtlgb6+a5EkCfiw7FIq02kzFWyzaP5sN5MvZmh+PDdbkkx60qf+7cSou IPv3CSgsQPnXHTRyiGthpNo4hQW/aArdZbz4nvWxlVUSc0fOofGXtKqLni7/tUYV jbbKiAyhTDtTqRf9I8McwbI85QN61UwNT1hrHwTmlRh3lbs6UQWD3lDylmVNIopX 9yjMiswSd7Vathje3IcjLFX1/8p+uoI7iine/8hY3jnds2uX1wXXlQPukPlt+tIb olF0hXu6saTVUPYjvp9jgsjXGjklI4mR3dE7jCkBekV8Fg3AGWzHCut5MlJqtw+Y ekqeshZH88bMMhq9NAI/Q6Gnxp3PxA== =I2HM -----END PGP SIGNATURE----- --xn57vvywhbh4vq4z--