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 C33491474C5; Thu, 13 Jun 2024 12:13:29 +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=1718280809; cv=none; b=JRarFastJmSPm7iKw6yZ1MjwxFeA5nj98c3TpJ5sA6k+amgGzYq48QS3TkbMyhPVzrjAK3FZ+2KIiZT00oa9DPqAv9aU26PTqFyF4e9xY0lco/reobe7gLUZJ619qvKdEiYJSbkht9yPJmVaG8dl0RVH4rwPmieWDvht26iRQDs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718280809; c=relaxed/simple; bh=lqu/KcqQyglRpyLkofABUYY4KBloH3EeObWgK50LMkQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ujYyUqy57/TemOFhZUdruZAuqOn1ay3nzo4VsO491njNR+bcZphsycirwXXIjzAIJzqFOLw3FqP9JUY9dRjauyLHoMyI53AJpWkcEmmN1x6NoBEC8D5LbmevU0CSboDT4qQkfcgtjtoBUKZhTffMCXZdJ564U/E+TB11h2a4QT0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OEJGnozn; 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="OEJGnozn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00FB3C2BBFC; Thu, 13 Jun 2024 12:13:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718280809; bh=lqu/KcqQyglRpyLkofABUYY4KBloH3EeObWgK50LMkQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OEJGnoznJqFwhFhmSWWmbEfzhRTVr1XdxM2gr1bYElqS72gbKUsLMOqdyccOM/Np2 Y5wCvYEXinrCUDeyNCtj4adaHnasp5BXV7Ij9mmggwzvfuY3I16aSm7c5xadTAx8J1 xr/cm5BON+xSHxvinOhqz40zP11ODCrH7+h6dVqE= 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 5.10 042/317] scsi: ufs: qcom: Perform read back after writing unipro mode Date: Thu, 13 Jun 2024 13:31:00 +0200 Message-ID: <20240613113249.176892862@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240613113247.525431100@linuxfoundation.org> References: <20240613113247.525431100@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 5.10-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/scsi/ufs/ufs-qcom.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c index ef8d721022da5..7b8e591265671 100644 --- a/drivers/scsi/ufs/ufs-qcom.c +++ b/drivers/scsi/ufs/ufs-qcom.c @@ -245,9 +245,6 @@ 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