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 8DA731474BF; Thu, 13 Jun 2024 11:56:10 +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=1718279770; cv=none; b=RZNqJI3+ZL/RPAhfs4ukZ3zk5zeMMEMptrg/WNKjOZN8D+mczGNEM1lZVm4JgdvhyCxIkWWqaKFV4+2eNhtp/rmARocXxKHRt9HibQz/hvLnWfbBiU65pXGOfU60cxGhJQxuL/2MWITJstNqdmNYVVem1Unk9mZmS9moPOPaDAo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718279770; c=relaxed/simple; bh=GSRkBDiL0iOxl7BEzPFAQDbhCZX5IrolTNdTTwFPMMo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J3vOZgp4p+Hsqb4ickIbeDtnUeRxtXp+pJ/xKZ2XIiTePpdijGsUOGKQctrxQL1xWPijuRn58JIgS5BZxem6XYk2ypSZmE25yet9DzKsaWXuFQoyAEkzIaYMa9q6UhEVlgoohzqC15iNWXNS+hTGibK6aSPXSwQ4WsieUKPX/TQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=t5uM/Vey; 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="t5uM/Vey" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10837C2BBFC; Thu, 13 Jun 2024 11:56:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718279770; bh=GSRkBDiL0iOxl7BEzPFAQDbhCZX5IrolTNdTTwFPMMo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=t5uM/Veygoibjt97zibNmapl7IbP4Hi1/ERwqX480+rhqyh+rc4xWXoRuDIBVymAJ wst6+wMft4k+lOetl6j+yDT75AasmJM3G0sMy4Ljw2BMM4CyrVcR4tgEFOn1vCo1rK Pmcaxkter5Df+bx/7zTbxzsa2s2r0w9FryEdliDI= 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 5.4 031/202] scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV Date: Thu, 13 Jun 2024 13:32:09 +0200 Message-ID: <20240613113228.974449974@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240613113227.759341286@linuxfoundation.org> References: <20240613113227.759341286@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 5.4-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 6feeb0faf123a..9d6bb47168706 100644 --- a/drivers/scsi/ufs/cdns-pltfrm.c +++ b/drivers/scsi/ufs/cdns-pltfrm.c @@ -56,7 +56,7 @@ 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