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 05D617B for ; Wed, 23 Nov 2022 08:59:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48FF4C433C1; Wed, 23 Nov 2022 08:59:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669193948; bh=xgVPU+roTiY3lq8wwHqlqta0cuZXORGBp20GZ7jDlw0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T5R/DdfHQAHoG5Lb2fIvxIzNFvvqRdZcbdr/0whAJrUxFWmX3JKDTkvUIC5vOnKys fqOlRnRh4PUVizGnTD8UrrP4BA6eOv3d8t3u7617msvBwxLDszAbF+GivziuH1h2sa 4obOxz8mzsw+vx3iupYczdmS/Ei7DifZGX61pBjc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peter Rosin , Tudor Ambarus , Nicolas Ferre , Vinod Koul Subject: [PATCH 4.14 29/88] dmaengine: at_hdmac: Dont allow CPU to reorder channel enable Date: Wed, 23 Nov 2022 09:50:26 +0100 Message-Id: <20221123084549.493640121@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084548.535439312@linuxfoundation.org> References: <20221123084548.535439312@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Tudor Ambarus commit 580ee84405c27d6ed419abe4d2b3de1968abdafd upstream. at_hdmac uses __raw_writel for register writes. In the absence of a barrier, the CPU may reorder the register operations. Introduce a write memory barrier so that the CPU does not reorder the channel enable, thus the start of the transfer, without making sure that all the pre-required register fields are already written. Fixes: dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller") Reported-by: Peter Rosin Signed-off-by: Tudor Ambarus Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/ Acked-by: Nicolas Ferre Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com Link: https://lore.kernel.org/r/20221025090306.297886-14-tudor.ambarus@microchip.com Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- drivers/dma/at_hdmac.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -252,6 +252,8 @@ static void atc_dostart(struct at_dma_ch ATC_SPIP_BOUNDARY(first->boundary)); channel_writel(atchan, DPIP, ATC_DPIP_HOLE(first->dst_hole) | ATC_DPIP_BOUNDARY(first->boundary)); + /* Don't allow CPU to reorder channel enable. */ + wmb(); dma_writel(atdma, CHER, atchan->mask); vdbg_dump_regs(atchan);