From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30C301A2C3A; Thu, 6 Jun 2024 14:13:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717683209; cv=none; b=gNBAIUk00XE1i1fBrVcsLmw2yZrMTmXbmY/uQVDucwvk6QAqzUJCwhP/4lku5FcVbZLYsYahyKg1WMsnd91Xo5h/LCVcrikxkW9qA4390FiNAHa1cPUZNjs1yRRnIfVwUngINZJ6qVVYsISrvyjSDXCt/7rUAb29dqDWJYHp5Dg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717683209; c=relaxed/simple; bh=dDxJFGgJH6sP+Ys79DPRk1CC58FMMT9ytRdoxnfLfMk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eekc7Kbygt4BD7b+mSE7AlLWA9p1xM+Fiu4HdmV1fKCTcThxmiceHrjJSKvky8KVByIm3bYDrEm2U/+2VG8E8lTyxXQlq3EW1cTSInS+gewoY3elPCqKWTO5YD1gp+yzjOt+FjBoJENmWA0sPzbuIinmOapDGPppC9FXlnP4h1w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YDcJHrmV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YDcJHrmV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CFFBC32781; Thu, 6 Jun 2024 14:13:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1717683209; bh=dDxJFGgJH6sP+Ys79DPRk1CC58FMMT9ytRdoxnfLfMk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YDcJHrmVGR+gMpOVLfLP517SBr0jKlLiVNmL82oW87OpJc/Y4bvWUg1K1orA+YC0v crl0d4xNhluBKrLKVDjpJ48lSG31qYFVmBxy90VP2h7wTcM9XifOme6+9uVBrV4OTS oYUWbX4x5UG4J4443KbaNejA78g3id/ic0pG6Utk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Halaney , Manivannan Sadhasivam , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 6.6 152/744] scsi: ufs: qcom: Perform read back after writing unipro mode Date: Thu, 6 Jun 2024 15:57:04 +0200 Message-ID: <20240606131737.289121883@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240606131732.440653204@linuxfoundation.org> References: <20240606131732.440653204@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Halaney [ Upstream commit 823150ecf04f958213cf3bf162187cd1a91c885c ] Currently, the QUNIPRO_SEL bit is written to and then an mb() is used to ensure that completes before continuing. mb() ensures that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring this bit has taken effect on the device is to perform a read back to force it to make it all the way to the device. This is documented in device-io.rst and a talk by Will Deacon on this can be seen over here: https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678 But, there's really no reason to even ensure completion before continuing. The only requirement here is that this write is ordered to this endpoint (which readl()/writel() guarantees already). For that reason the mb() can be dropped altogether without anything forcing completion. Fixes: f06fcc7155dc ("scsi: ufs-qcom: add QUniPro hardware support and power optimizations") Signed-off-by: Andrew Halaney Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-4-181252004586@redhat.com Reviewed-by: Manivannan Sadhasivam Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/ufs/host/ufs-qcom.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 559b4cab16a3e..1f2a64d797c79 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -373,9 +373,6 @@ static void ufs_qcom_select_unipro_mode(struct ufs_qcom_host *host) if (host->hw_ver.major >= 0x05) ufshcd_rmwl(host->hba, QUNIPRO_G4_SEL, 0, REG_UFS_CFG0); - - /* make sure above configuration is applied before we return */ - mb(); } /* -- 2.43.0