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 3A768195; Thu, 13 Jun 2024 12:30:07 +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=1718281807; cv=none; b=al1ryHq5umo8zTz3GUTt05UUy3ck2RiGCssnVquyFAs0cdA8bDPSPrm56rpUJheJeFgn3D1xrRP5cDW2IrmsnVZThW264eusZRZ427qB9jgqJfK/84JFxX/Vq5VRN3Uf8x8730gCDIURpo3XkuIzJRTnVlF7I3DkLWo7O/m2RGs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718281807; c=relaxed/simple; bh=Sht7GassD0YWezh8oCMb4ge3ByxUwFESHICmUHQCBFM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oFxCFl6LtDMnN9TmH7kKPdhLEmZQ9F7O+L+GT4vIfXT0IA7vTZrdigiz1Q/wP7SuOfaaA9MU3Mjvsy98HLSzhJhocxm3wO0AkgtVVCdZRAKNbXO+vVsk+Rb+WREPPpmnRoroTxsBjY1tHuiEB52EYyVT0sN3k5QhCGew3NJMI2M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=f6AbqFuB; 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="f6AbqFuB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADA9FC2BBFC; Thu, 13 Jun 2024 12:30:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718281807; bh=Sht7GassD0YWezh8oCMb4ge3ByxUwFESHICmUHQCBFM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f6AbqFuB8YffzzPxVIo5LhARi2IRnYtxmSdImqlqBUQviVihIy3q5GXEsOTup8r8x WuuJYGD5WDDnnbBXSy44n+bMTEWHowWR73EOWQu2bL2yTtuzuGzpoY4CQpB9RS8f8W Xri1znvPidF45ia2vdk8UXlqjLKFT9qpic3eOFoE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Manivannan Sadhasivam , Andrew Halaney , Bart Van Assche , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 5.15 063/402] scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV Date: Thu, 13 Jun 2024 13:30:20 +0200 Message-ID: <20240613113304.594840494@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240613113302.116811394@linuxfoundation.org> References: <20240613113302.116811394@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Halaney [ Upstream commit b715c55daf598aac8fa339048e4ca8a0916b332e ] Currently, HCLKDIV is written to and then completed with an mb(). 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 Let's do that to ensure the bit hits the device. Because the mb()'s purpose wasn't to add extra ordering (on top of the ordering guaranteed by writel()/readl()), it can safely be removed. Fixes: d90996dae8e4 ("scsi: ufs: Add UFS platform driver for Cadence UFS") Reviewed-by: Manivannan Sadhasivam Signed-off-by: Andrew Halaney Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-6-181252004586@redhat.com Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/scsi/ufs/cdns-pltfrm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/ufs/cdns-pltfrm.c b/drivers/scsi/ufs/cdns-pltfrm.c index 7da8be2f35c42..07a2580e4e56c 100644 --- a/drivers/scsi/ufs/cdns-pltfrm.c +++ b/drivers/scsi/ufs/cdns-pltfrm.c @@ -136,7 +136,7 @@ static int cdns_ufs_set_hclkdiv(struct ufs_hba *hba) * Make sure the register was updated, * UniPro layer will not work with an incorrect value. */ - mb(); + ufshcd_readl(hba, CDNS_UFS_REG_HCLKDIV); return 0; } -- 2.43.0