From patchwork Mon May 4 17:57:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 226366 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 563F2C47259 for ; Mon, 4 May 2020 18:11:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39C9C2078C for ; Mon, 4 May 2020 18:11:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615888; bh=bDrhjzhTskjV7kPXv5v9McXEoLe8VDFr0GW1kaT3njM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zsgWOp3jDL7QhRKd7vVRLT3Hn9CjIOUgwzGTgi6DgFoYApGOt4KvR0mne7kc1EG+b wmimHU8OKs9fr6kfLOcFv2HbyaRDG30VEk2BBVwlkiFMLayN+DkwSsh+7e1qbt5Ro5 fc9lSgMLMJS4CGJZAOmbmEXqhXa7ZnRTSxDinQ1o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730937AbgEDSFa (ORCPT ); Mon, 4 May 2020 14:05:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:35252 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731817AbgEDSF2 (ORCPT ); Mon, 4 May 2020 14:05:28 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0C86D206B8; Mon, 4 May 2020 18:05:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615526; bh=bDrhjzhTskjV7kPXv5v9McXEoLe8VDFr0GW1kaT3njM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X5p8PIEcDvAAJnJ1SFXFtupV754GQrJp7V1nokR2Af1sleQif55KEKdAMIhedn+kk MlU5JmJk4U66uUiZh9ytrwlIY1uCOme4Jkx883Nyx9QJpcB9haRAXkOTWV3q5cDqK3 usThdjeRBA54e720pLpTJM4inhWl64ayn61apDq0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?utf-8?q?Marek_Beh=C3=BAn?= , Ulf Hansson Subject: [PATCH 5.6 17/73] mmc: sdhci-xenon: fix annoying 1.8V regulator warning Date: Mon, 4 May 2020 19:57:20 +0200 Message-Id: <20200504165505.044101855@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200504165501.781878940@linuxfoundation.org> References: <20200504165501.781878940@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Marek Behún commit bb32e1987bc55ce1db400faf47d85891da3c9b9f upstream. For some reason the Host Control2 register of the Xenon SDHCI controller sometimes reports the bit representing 1.8V signaling as 0 when read after it was written as 1. Subsequent read reports 1. This causes the sdhci_start_signal_voltage_switch function to report 1.8V regulator output did not become stable When CONFIG_PM is enabled, the host is suspended and resumend many times, and in each resume the switch to 1.8V is called, and so the kernel log reports this message annoyingly often. Do an empty read of the Host Control2 register in Xenon's .voltage_switch method to circumvent this. This patch fixes this particular problem on Turris MOX. Signed-off-by: Marek Behún Fixes: 8d876bf472db ("mmc: sdhci-xenon: wait 5ms after set 1.8V...") Cc: stable@vger.kernel.org # v4.16+ Link: https://lore.kernel.org/r/20200420080444.25242-1-marek.behun@nic.cz Signed-off-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman --- drivers/mmc/host/sdhci-xenon.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/drivers/mmc/host/sdhci-xenon.c +++ b/drivers/mmc/host/sdhci-xenon.c @@ -235,6 +235,16 @@ static void xenon_voltage_switch(struct { /* Wait for 5ms after set 1.8V signal enable bit */ usleep_range(5000, 5500); + + /* + * For some reason the controller's Host Control2 register reports + * the bit representing 1.8V signaling as 0 when read after it was + * written as 1. Subsequent read reports 1. + * + * Since this may cause some issues, do an empty read of the Host + * Control2 register here to circumvent this. + */ + sdhci_readw(host, SDHCI_HOST_CONTROL2); } static const struct sdhci_ops sdhci_xenon_ops = {