From patchwork Wed Mar 19 05:55:50 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sekhar Nori X-Patchwork-Id: 3857311 X-Patchwork-Delegate: vinod.koul@intel.com Return-Path: X-Original-To: patchwork-dmaengine@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C3CB6BF540 for ; Wed, 19 Mar 2014 18:04:10 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4E416200DC for ; Wed, 19 Mar 2014 18:04:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7380D200E1 for ; Wed, 19 Mar 2014 18:04:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752547AbaCSF4O (ORCPT ); Wed, 19 Mar 2014 01:56:14 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:57239 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751122AbaCSF4M (ORCPT ); Wed, 19 Mar 2014 01:56:12 -0400 Received: from dlelxv90.itg.ti.com ([172.17.2.17]) by comal.ext.ti.com (8.13.7/8.13.7) with ESMTP id s2J5u76B027551; Wed, 19 Mar 2014 00:56:07 -0500 Received: from DLEE71.ent.ti.com (dlee71.ent.ti.com [157.170.170.114]) by dlelxv90.itg.ti.com (8.14.3/8.13.8) with ESMTP id s2J5u7DU006775; Wed, 19 Mar 2014 00:56:07 -0500 Received: from dflp33.itg.ti.com (10.64.6.16) by DLEE71.ent.ti.com (157.170.170.114) with Microsoft SMTP Server id 14.3.174.1; Wed, 19 Mar 2014 00:56:07 -0500 Received: from psplinux063.india.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp33.itg.ti.com (8.14.3/8.13.8) with ESMTP id s2J5u34P018517; Wed, 19 Mar 2014 00:56:04 -0500 From: Sekhar Nori To: Dan Williams , Vinod Koul CC: DMA Engine Mailing List , Linux DaVinci Mailing List , Jon Ringle , Alexander Holler , Linux OMAP Mailing List , Sekhar Nori , Joel Fernandes Subject: [PATCH 1/1] dma: edma: fix incorrect SG list handling Date: Wed, 19 Mar 2014 11:25:50 +0530 Message-ID: <1395208550-1603-1-git-send-email-nsekhar@ti.com> X-Mailer: git-send-email 1.7.10.1 MIME-Version: 1.0 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable 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 The code to handle any length SG lists calls edma_resume() even before edma_start() is called. This is incorrect because edma_resume() enables edma events on the channel after which CPU (in edma_start) cannot clear posted events by writing to ECR (per the EDMA user's guide). Because of this EDMA transfers fail to start if due to some reason there is a pending EDMA event registered even before EDMA transfers are started. This can happen if an EDMA event is a byproduct of device initialization. Fix this by calling edma_resume() only if it is not the first batch of MAX_NR_SG elements. Without this patch, MMC/SD fails to function on DA850 EVM with DMA. The behaviour is triggered by specific IP and this can explain why the issue was not reported before (example with MMC/SD on AM335x). Tested on DA850 EVM and AM335x EVM-SK using MMC/SD card. Cc: stable@vger.kernel.org # v3.12.x+ Cc: Joel Fernandes Acked-by: Joel Fernandes Tested-by: Jon Ringle Tested-by: Alexander Holler Reported-by: Jon Ringle Signed-off-by: Sekhar Nori --- Same as the version send previously (which did not make into all mailing lists). Commit message updates with tested-by and acks received. drivers/dma/edma.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index cd8da45..bf5ad0f 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -182,11 +182,13 @@ static void edma_execute(struct edma_chan *echan) echan->ecc->dummy_slot); } - edma_resume(echan->ch_num); - if (edesc->processed <= MAX_NR_SG) { dev_dbg(dev, "first transfer starting %d\n", echan->ch_num); edma_start(echan->ch_num); + } else { + dev_dbg(dev, "chan: %d: completed %d elements, resuming\n", + echan->ch_num, edesc->processed); + edma_resume(echan->ch_num); } /*