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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 4BBBDC6778A for ; Thu, 5 Jul 2018 11:22:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 082742244E for ; Thu, 5 Jul 2018 11:22:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=agner.ch header.i=@agner.ch header.b="SLhGlWBb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 082742244E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=agner.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852AbeGELWh (ORCPT ); Thu, 5 Jul 2018 07:22:37 -0400 Received: from mail.kmu-office.ch ([178.209.48.109]:38234 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753409AbeGELWf (ORCPT ); Thu, 5 Jul 2018 07:22:35 -0400 Received: from webmail.kmu-office.ch (unknown [IPv6:2a02:418:6a02::a3]) by mail.kmu-office.ch (Postfix) with ESMTPSA id D55815C16B5; Thu, 5 Jul 2018 13:22:33 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=agner.ch; s=dkim; t=1530789753; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=G3Dy8qoagLqfR3gEnIq2Edxkl0Y3vHbBz1M48+t9uYQ=; b=SLhGlWBbUqxZvR+RUj+GTp6ZxAYW9vLekFhJFXBV5jvevEQtvN+Nr/g2KcNpuHNvla5d90 wx8QOdhcdmyh2sr+jBaj2WF0Gg0dIqjWZp5Q+3JGL/kRpgNT6vaGfB7GqBf3SQ9TiyB8nB wTD0bSXaNcqKz8rct3/3NF3HcGEGh+o= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Date: Thu, 05 Jul 2018 13:22:33 +0200 From: Stefan Agner To: Ulf Hansson Cc: Adrian Hunter , Fabio Estevam , Haibo Chen , Aisheng Dong , Michael Trimarchi , Russell King , linux-mmc@vger.kernel.org, Linux Kernel Mailing List Subject: Re: [PATCH v2] mmc: sdhci-esdhc-imx: allow 1.8V modes without 100/200MHz pinctrl states In-Reply-To: References: <20180704150745.21003-1-stefan@agner.ch> Message-ID: <69f6122b8a69f1ab41d2ef8274321689@agner.ch> X-Sender: stefan@agner.ch User-Agent: Roundcube Webmail/1.3.4 X-Spamd-Result: default: False [-3.10 / 15.00]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; TAGGED_RCPT(0.00)[kernel]; MIME_GOOD(-0.10)[text/plain]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_SEVEN(0.00)[9]; FROM_EQ_ENVFROM(0.00)[]; DKIM_SIGNED(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_ZERO(0.00)[0]; ASN(0.00)[asn:29691, ipnet:2a02:418::/29, country:CH]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%]; ARC_NA(0.00)[] Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05.07.2018 11:48, Ulf Hansson wrote: > On 4 July 2018 at 17:18, Stefan Agner wrote: >> On 04.07.2018 17:07, Stefan Agner wrote: >>> If pinctrl nodes for 100/200MHz are missing, the controller should >>> not select any mode which need signal frequencies 100MHz or higher. >>> To prevent such speed modes the driver currently uses the quirk flag >>> SDHCI_QUIRK2_NO_1_8_V. This works nicely for SD cards since 1.8V >>> signaling is required for all faster modes and slower modes use 3.3V >>> signaling only. >>> >>> However, there are eMMC modes which use 1.8V signaling and run below >>> 100MHz, e.g. DDR52 at 1.8V. With using SDHCI_QUIRK2_NO_1_8_V this >>> mode is prevented. When using a fixed 1.8V regulator as vqmmc-supply >>> the stack has no valid mode to use. In this tenuous situation the >>> kernel continuously prints voltage switching errors: >>> mmc1: Switching to 3.3V signalling voltage failed >>> >>> Avoid using SDHCI_QUIRK2_NO_1_8_V and prevent faster modes by >>> altering the SDHCI capability register. With that the stack is able >>> to select 1.8V modes even if no faster pinctrl states are available: >>> # cat /sys/kernel/debug/mmc1/ios >>> ... >>> timing spec: 8 (mmc DDR52) >>> signal voltage: 1 (1.80 V) >>> ... >>> >>> Link: http://lkml.kernel.org/r/20180628081331.13051-1-stefan@agner.ch >>> Signed-off-by: Stefan Agner >>> --- >> >> Btw, I still get the switching error once during boot-up: >> mmc1: Switching to 3.3V signalling voltage failed > > I guess the this happens then also at system resume? > > The core tries first with 3.3 then if it fails, it continues with 1.8V, etc. > >> >> This is due to the call from mmc_set_initial_signal_voltage. It is a bit >> unfortunate since this is printed as a warning. Not sure if that could >> be prevented somehow? > > Seems like SDHCI_SIGNALING_330 should not be set, unless 3.3V I/O is > supported. That should avoid SDHCI from trying and instead just > returning an error code immediately. > > This seems like a generic issues for all SDHCI variant drivers. Hm, can we resolve this in a generic fashion? E.g something like this in sdhci_setup_host(): if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 3200000, 3450000)) host->flags &= ~SDHCI_SIGNALING_330; -- Stefan