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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7548BCCA485 for ; Tue, 7 Jun 2022 21:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1381448AbiFGVko (ORCPT ); Tue, 7 Jun 2022 17:40:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377789AbiFGUu5 (ORCPT ); Tue, 7 Jun 2022 16:50:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F316E1FD281; Tue, 7 Jun 2022 11:40:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DDCB66159D; Tue, 7 Jun 2022 18:40:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED9E5C385A2; Tue, 7 Jun 2022 18:40:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654627237; bh=NEWA8RjCSVtHMZ/gIwVntnVIbb+hxC/r1ater9BUcEo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xtbh3F3mMPxjECDqoPs2rtEgLfIeLNTKJgrQxfXYOBxREBBwZIkrMUgUjfgRV1hLb n0EPXiuIHy8FlmFNtuJNF/YKhAO+deJ5d13E1m1+xwj1GxRSDR968lx4AsgfeE2pX2 Nxt4cHhfINswwMh5ebQlul6UHhXFXFE+ruoDchqI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bjorn Andersson , Manivannan Sadhasivam , "Martin K. Petersen" Subject: [PATCH 5.17 667/772] scsi: ufs: qcom: Add a readl() to make sure ref_clk gets enabled Date: Tue, 7 Jun 2022 19:04:19 +0200 Message-Id: <20220607165008.714800064@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164948.980838585@linuxfoundation.org> References: <20220607164948.980838585@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Manivannan Sadhasivam commit 8eecddfca30e1651dc1c74531ed5eef21dcce7e3 upstream. In ufs_qcom_dev_ref_clk_ctrl(), it was noted that the ref_clk needs to be stable for at least 1us. Even though there is wmb() to make sure the write gets "completed", there is no guarantee that the write actually reached the UFS device. There is a good chance that the write could be stored in a Write Buffer (WB). In that case, even though the CPU waits for 1us, the ref_clk might not be stable for that period. So lets do a readl() to make sure that the previous write has reached the UFS device before udelay(). Also, the wmb() after writel_relaxed() is not really needed. Both writel() and readl() are ordered on all architectures and the CPU won't speculate instructions after readl() due to the in-built control dependency with read value on weakly ordered architectures. So it can be safely removed. Link: https://lore.kernel.org/r/20220504084212.11605-4-manivannan.sadhasivam@linaro.org Fixes: f06fcc7155dc ("scsi: ufs-qcom: add QUniPro hardware support and power optimizations") Cc: stable@vger.kernel.org Reviewed-by: Bjorn Andersson Signed-off-by: Manivannan Sadhasivam Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/ufs/ufs-qcom.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/scsi/ufs/ufs-qcom.c +++ b/drivers/scsi/ufs/ufs-qcom.c @@ -682,8 +682,11 @@ static void ufs_qcom_dev_ref_clk_ctrl(st writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio); - /* ensure that ref_clk is enabled/disabled before we return */ - wmb(); + /* + * Make sure the write to ref_clk reaches the destination and + * not stored in a Write Buffer (WB). + */ + readl(host->dev_ref_clk_ctrl_mmio); /* * If we call hibern8 exit after this, we need to make sure that