From patchwork Mon May 4 17:57:22 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: 226433 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=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 25320C3A5A9 for ; Mon, 4 May 2020 18:00:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F2DDD206B8 for ; Mon, 4 May 2020 18:00:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615257; bh=w/JwMb7JVHqYplPPoNYvno00KImVTLDxu+5qtPyfeg0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bAV9zF9ZiVRkrUTlbVi7IaAKu9aevPPiNQhw4VsV0BTGbQdYX4fW4M/h+1BB6gIGG Vs9woOSIE9mYouHjuOQTlKqorHwjjE0zpL+xqJ6zokL/7oI25IUNI/hyDYkXngYunf c4UJx5k1B6emFNC4tvliVEf1bRmRifIyGPLqiKIM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731082AbgEDSAz (ORCPT ); Mon, 4 May 2020 14:00:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:55936 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730575AbgEDSAy (ORCPT ); Mon, 4 May 2020 14:00:54 -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 D6D0F2078C; Mon, 4 May 2020 18:00:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615253; bh=w/JwMb7JVHqYplPPoNYvno00KImVTLDxu+5qtPyfeg0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HmlMd9JOYay/mzFcDxHYvxfiY1iR5LVyQjTQqQvsJuJSPqSlTWjchCAvonTD8ZWEn Gx9VIziShyDeraMFW48jLboF2p0pAYF5QR7h4sNyQtFKJ3JOSt1OXZnQ4uhiFHNkxz kF8BzWx5EJtL05NB4veNrFkzMvuURANKUJqYnrLY= 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 4.14 08/26] mmc: sdhci-xenon: fix annoying 1.8V regulator warning Date: Mon, 4 May 2020 19:57:22 +0200 Message-Id: <20200504165444.563485569@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200504165442.494398840@linuxfoundation.org> References: <20200504165442.494398840@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 @@ -238,6 +238,16 @@ 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 = {