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 A054BC433B4 for ; Fri, 9 Apr 2021 10:54:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D910610E7 for ; Fri, 9 Apr 2021 10:54:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233288AbhDIKym (ORCPT ); Fri, 9 Apr 2021 06:54:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:59252 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232087AbhDIKym (ORCPT ); Fri, 9 Apr 2021 06:54:42 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 875E9AF9E; Fri, 9 Apr 2021 10:54:28 +0000 (UTC) Message-ID: <2dbb9e8c1f1e107712b05e36aa1b244329381425.camel@suse.de> Subject: Re: [PATCH 4/4] ARM: dts: Fix-up EMMC2 controller's frequency From: Nicolas Saenz Julienne To: Alan Cooper , Florian Fainelli , Scott Branden Cc: Stefan Wahren , Nicolas Saenz Julienne , "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" , linux-mmc , DTML , BCM Kernel Feedback , linux-rpi-kernel@lists.infradead.org, Florian Fainelli , phil@raspberrypi.com, Tim Gover , Adrian Hunter , Linux Kernel Mailing List , Ulf Hansson , Rob Herring Date: Fri, 09 Apr 2021 12:54:26 +0200 In-Reply-To: References: <20210322185816.27582-1-nsaenz@kernel.org> <20210322185816.27582-5-nsaenz@kernel.org> <401100ea-90ad-57b1-50da-967118a090da@i2se.com> <78dec30c052e9bb76e52c38f3da5af371e5d65f5.camel@suse.de> <2d2a2638-8213-5d6e-0a3a-927ed5bb2ed7@i2se.com> <4d4e3de99dbee711cf47878bf98a7cc34c3f1e65.camel@suse.de> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-KxZS3sx9rZTVwyYp0yY2" User-Agent: Evolution 3.40.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --=-KxZS3sx9rZTVwyYp0yY2 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi again, On Wed, 2021-04-07 at 16:37 -0400, Alan Cooper wrote: > Nicolas, >=20 > I got a better description of the failure and it looks like the bus > clock needs to be limited to 300KHz for a 500MHz core clock. > What's happening is that an internal reset sequence is needed after a > command timeout and the reset signal needs to be asserted for at least > 2 ticks of the bus clock. This is done using a 12 bit counter clocked > by the core clock. That means a 500MHz core clock produces a 122KHz > reset signal which is too fast for 2 ticks of the 200KHz bus clock > (100KHz) but is okay for the 300KHz (150Khz) bus clock. Is there any value in implementing this in a generic way? That is, will a S= oC other than BCM2711 ever need this? Otherwise I can simply limit BCM2711's sdhci-iproc min clk frequency to 300KHz and call it a day. The alternative is something the likes of: min_clk =3D clk_get_rate(core_bus) >> 11; But it involves updating the bindings and DT. Regards, Nicolas --=-KxZS3sx9rZTVwyYp0yY2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAmBwMmIACgkQlfZmHno8 x/7ntQgAiD7GcI2zPvYkkdlBBtohEpENZTydgEPLuTHhXzablbGyC/GT5EJ5Pr+K iXL1Qlv5xpovPxWIx5hGdFLY/RbFSI4s4C7f2HYoPgRwwwn5AuCmuVwcL+tKkJ6d sD1dmGUJo/uMQ/P3oT0G0Ea4yuz2LSIXeq/K8PEqWLEl+Aaw3ciINqYeUlWOuGcB jPTJlSOgYj5rzYAskiRKcTiUp1fVbe9hiMi5ppft4fnJ1nYIU6wQcDxCo1WUUDhe Op/DdFTTzW+JP3mSmtr/EzVp5ldrupNFTcOzQODhDb4lEsO/ALBMMiKKhAlJVh0j 0NofzFbS3vtJ0ffpD7TnoQlkKSIE7g== =pOg3 -----END PGP SIGNATURE----- --=-KxZS3sx9rZTVwyYp0yY2--