Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751832AbdIUS33 (ORCPT ); Thu, 21 Sep 2017 14:29:29 -0400 Received: from fllnx210.ext.ti.com ([198.47.19.17]:39652 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751605AbdIUS31 (ORCPT ); Thu, 21 Sep 2017 14:29:27 -0400 Subject: Re: [PATCH] dmaengine: edma: Reject slave configs using a buswidth of 8 and larger To: Vinod Koul , =?UTF-8?Q?Stefan_Br=c3=bcns?= References: <20170917142510.3111-1-stefan.bruens@rwth-aachen.de> <20170921171743.GI30097@localhost> CC: , , Dan Williams From: Peter Ujfalusi Message-ID: <13ff5f5c-3872-4af5-1baf-205fe01bb0f2@ti.com> Date: Thu, 21 Sep 2017 21:29:27 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170921171743.GI30097@localhost> Content-Type: text/plain; charset="utf-8" X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v8LITXDi025113 Content-Length: 1727 Lines: 55  Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki On 2017-09-21 20:17, Vinod Koul wrote: > On Sun, Sep 17, 2017 at 04:25:10PM +0200, Stefan Brüns wrote: >> The driver would happily accept buswidth of 16/32/64 bytes and program >> garbage to its registers. > > Peter? Well, eDMA as such has no limitation on the buswidth, the addr_width become ACNT, counter for the inner loop - which we use to represent the word length. In theory we could support 32K-1 long word with eDMA, which we actually do in case of memcpy. But the driver does state that it supports bus width of 1, 2, 3 and 4 bytes. These are form the past and I never felt the need to check them. I think it is fine to reject salve config when asking for longer dev width. I might revisit later if the need comes.. Acked-by: Peter Ujfalusi > >> >> Signed-off-by: Stefan Brüns >> --- >> drivers/dma/edma.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c >> index 3879f80a4815..c944ea339425 100644 >> --- a/drivers/dma/edma.c >> +++ b/drivers/dma/edma.c >> @@ -887,8 +887,8 @@ static int edma_slave_config(struct dma_chan *chan, >> { >> struct edma_chan *echan = to_edma_chan(chan); >> >> - if (cfg->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES || >> - cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES) >> + if (cfg->src_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES || >> + cfg->dst_addr_width >= DMA_SLAVE_BUSWIDTH_8_BYTES) >> return -EINVAL; >> >> memcpy(&echan->cfg, cfg, sizeof(echan->cfg)); >> -- >> 2.14.1 >> > - Péter