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 2050DC3279B for ; Wed, 4 Jul 2018 15:18:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD73F224E6 for ; Wed, 4 Jul 2018 15:18:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=agner.ch header.i=@agner.ch header.b="fa10OSSm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BD73F224E6 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 S1752635AbeGDPSU (ORCPT ); Wed, 4 Jul 2018 11:18:20 -0400 Received: from mail.kmu-office.ch ([178.209.48.109]:57724 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752145AbeGDPST (ORCPT ); Wed, 4 Jul 2018 11:18:19 -0400 Received: from webmail.kmu-office.ch (unknown [IPv6:2a02:418:6a02::a3]) by mail.kmu-office.ch (Postfix) with ESMTPSA id 01FDC5C015F; Wed, 4 Jul 2018 17:18:17 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=agner.ch; s=dkim; t=1530717497; 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=JGblaBr6sob28U6hVnYV5ySgV1comTQAEG+kVmRsIf8=; b=fa10OSSmPPmzQ/0jXMprApYrTATN+zyEyRg34POkvT/Ip2ag4Gw8ix34PXodAJ9SWUOmT2 +MZsSTjbiD+nim1QWenIxc2Ut/FERBflFACfUkcP9dq/bitG4tLzSzl52ts7U3L0MmVL+4 JGSHPtU+PB5eXsQk85JYt+pLD6iEEFo= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Date: Wed, 04 Jul 2018 17:18:15 +0200 From: Stefan Agner To: adrian.hunter@intel.com, ulf.hansson@linaro.org Cc: fabio.estevam@nxp.com, haibo.chen@nxp.com, aisheng.dong@nxp.com, michael@amarulasolutions.com, rmk+kernel@armlinux.org.uk, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mmc: sdhci-esdhc-imx: allow 1.8V modes without 100/200MHz pinctrl states In-Reply-To: <20180704150745.21003-1-stefan@agner.ch> References: <20180704150745.21003-1-stefan@agner.ch> Message-ID: 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)[]; BAYES_HAM(-3.00)[100.00%]; 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)[]; RCVD_COUNT_ZERO(0.00)[0]; ASN(0.00)[asn:29691, ipnet:2a02:418::/29, country:CH]; TO_DN_NONE(0.00)[]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[] Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 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 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? -- Stefan > drivers/mmc/host/sdhci-esdhc-imx.c | 21 +++++++++------------ > 1 file changed, 9 insertions(+), 12 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c > b/drivers/mmc/host/sdhci-esdhc-imx.c > index 20a420b765b3..e96d969ab2c3 100644 > --- a/drivers/mmc/host/sdhci-esdhc-imx.c > +++ b/drivers/mmc/host/sdhci-esdhc-imx.c > @@ -312,6 +312,15 @@ static u32 esdhc_readl_le(struct sdhci_host *host, int reg) > > if (imx_data->socdata->flags & ESDHC_FLAG_HS400) > val |= SDHCI_SUPPORT_HS400; > + > + /* > + * Do not advertise faster UHS modes if there are no > + * pinctrl states for 100MHz/200MHz. > + */ > + if (IS_ERR_OR_NULL(imx_data->pins_100mhz) || > + IS_ERR_OR_NULL(imx_data->pins_200mhz)) > + val &= ~(SDHCI_SUPPORT_SDR50 | SDHCI_SUPPORT_DDR50 > + | SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_HS400); > } > } > > @@ -1157,18 +1166,6 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev, > ESDHC_PINCTRL_STATE_100MHZ); > imx_data->pins_200mhz = pinctrl_lookup_state(imx_data->pinctrl, > ESDHC_PINCTRL_STATE_200MHZ); > - if (IS_ERR(imx_data->pins_100mhz) || > - IS_ERR(imx_data->pins_200mhz)) { > - dev_warn(mmc_dev(host->mmc), > - "could not get ultra high speed state, work on normal mode\n"); > - /* > - * fall back to not supporting uhs by specifying no > - * 1.8v quirk > - */ > - host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V; > - } > - } else { > - host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V; > } > > /* call to generic mmc_of_parse to support additional capabilities */