From patchwork Mon Aug 17 13:08:55 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 7025051 Return-Path: X-Original-To: patchwork-dmaengine@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 5CF819F344 for ; Mon, 17 Aug 2015 13:09:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1E84220600 for ; Mon, 17 Aug 2015 13:09:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5A4D20582 for ; Mon, 17 Aug 2015 13:09:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754987AbbHQNJH (ORCPT ); Mon, 17 Aug 2015 09:09:07 -0400 Received: from xavier.telenet-ops.be ([195.130.132.52]:58915 "EHLO xavier.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751427AbbHQNJG (ORCPT ); Mon, 17 Aug 2015 09:09:06 -0400 Received: from ayla.of.borg ([84.193.93.87]) by xavier.telenet-ops.be with bizsmtp id 5p911r00Y1t5w8s01p91E9; Mon, 17 Aug 2015 15:09:04 +0200 Received: from ramsan.of.borg ([192.168.97.29] helo=ramsan) by ayla.of.borg with esmtp (Exim 4.82) (envelope-from ) id 1ZRK9s-0008OP-Vq; Mon, 17 Aug 2015 15:09:01 +0200 Received: from geert by ramsan with local (Exim 4.82) (envelope-from ) id 1ZRK9t-0007B2-Rw; Mon, 17 Aug 2015 15:09:01 +0200 From: Geert Uytterhoeven To: Vinod Koul , Dan Williams Cc: Arnd Bergmann , Tony Lindgren , Matt Porter , dmaengine@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] dmaengine: Stricter legacy checking in dma_request_slave_channel_compat() Date: Mon, 17 Aug 2015 15:08:55 +0200 Message-Id: <1439816935-27554-1-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 1.9.1 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP dma_request_slave_channel_compat() is meant for drivers that support both DT and legacy platform device based probing: if DT channel DMA setup fails, it will fall back to platform data based DMA channel setup, using hardcoded DMA channel IDs and a filter function. However, if the DTS doesn't provide a "dmas" property for the device, the fallback is also used. If the legacy filter function is not hardcoded in the DMA slave driver, but comes from platform data, it will be NULL. Then dma_request_slave_channel_compat() will succeed incorrectly, and return a DMA channel, as a NULL legacy filter function actually means "all channels are OK", not "do not match". Later, when trying to use that DMA channel, it will fail with: rcar-dmac e6700000.dma-controller: rcar_dmac_prep_slave_sg: bad parameter: len=1, id=-22 To fix this, ensure that both the filter function and the DMA channel ID are not NULL before using the legacy fallback. Note that some DMA slave drivers can handle this failure, and will fall back to PIO. See also commit 056f6c87028544de ("dmaengine: shdma: Make dummy shdma_chan_filter() always return false"), which fixed the same issue for the case where shdma_chan_filter() is hardcoded in a DMA slave driver. Suggested-by: Arnd Bergmann Signed-off-by: Geert Uytterhoeven --- include/linux/dmaengine.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index bdae84ab305bca59..6a22cf1b63c24ffb 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -1197,6 +1197,9 @@ static inline struct dma_chan if (chan) return chan; + if (!fn || !fn_param) + return NULL; + return __dma_request_channel(mask, fn, fn_param); } #endif /* DMAENGINE_H */