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 AE24B199255; Thu, 6 Jun 2024 14:13:31 +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=1717683211; cv=none; b=YoEUt0He/IZmVo0rPyoGcOhfguY9hq2r1JByM8jbKmUr39QNdS68mUZBvmR+M0NyiAVIPimmgksUY0/4s06jWa9qf6UOBUnHbdExi/m4z7H9cMk8COqFuRGN/DzszjTarSgRelM6JlJq3D4bPFxVl5vgZbCggbGtXsZUxpsZHTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717683211; c=relaxed/simple; bh=DFR/94AdFRj89DMGGmnrmqrsfyIGLwZCXwO3pu3eRfc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BO3ro7Bj89rVrdlGQnwPQxDF7T1FHGek7tkaXKtOdtx+QAXACKbh91FGJRO5jPTI201MyISSwhNrkb1Sl9QeedvmjLVcUarZCgthfe8XXyIp8imNwnP6RpRWL05ylwIuRvzE49EatwsEfv1bKnn/eMT2EQ/tg2X/7L7Xgg2brpg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BYfL/KmM; 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="BYfL/KmM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E781C32781; Thu, 6 Jun 2024 14:13:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1717683211; bh=DFR/94AdFRj89DMGGmnrmqrsfyIGLwZCXwO3pu3eRfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BYfL/KmM4dhBMjZdyOXXwFHLa5a4ouUVlq/oP7fBhwkgMHPa8Bi1JpTljl8yI5xTN bkCD3Sw7zzFbQWq2yov9zE7rK0x9OLFVGCRi1W45t+TJCEVILijJoqNGVYF/27ES8q /OHHt6LyzdJBRAceeV0IJhzO4Dmc6RVOjoc0jGPs= 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 6.6 154/744] scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV Date: Thu, 6 Jun 2024 15:57:06 +0200 Message-ID: <20240606131737.357840734@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: patches@lists.linux.dev 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 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/ufs/host/cdns-pltfrm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/ufs/host/cdns-pltfrm.c b/drivers/ufs/host/cdns-pltfrm.c index 2491e7e870283..56014ef302b49 100644 --- a/drivers/ufs/host/cdns-pltfrm.c +++ b/drivers/ufs/host/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