From patchwork Mon Mar 17 11:57:28 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sekhar Nori X-Patchwork-Id: 3843171 Return-Path: X-Original-To: patchwork-davinci@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 457179F334 for ; Mon, 17 Mar 2014 11:59:03 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 51AE2201BB for ; Mon, 17 Mar 2014 11:59:02 +0000 (UTC) Received: from comal.ext.ti.com (comal.ext.ti.com [198.47.26.152]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1B5972015D for ; Mon, 17 Mar 2014 11:59:00 +0000 (UTC) Received: from dflxv15.itg.ti.com ([128.247.5.124]) by comal.ext.ti.com (8.13.7/8.13.7) with ESMTP id s2HBw0D1011510; Mon, 17 Mar 2014 06:58:01 -0500 Received: from DLEE70.ent.ti.com (dlemailx.itg.ti.com [157.170.170.113]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id s2HBvxEr021764; Mon, 17 Mar 2014 06:57:59 -0500 Received: from dflp33.itg.ti.com (10.64.6.16) by DLEE70.ent.ti.com (157.170.170.113) with Microsoft SMTP Server id 14.3.174.1; Mon, 17 Mar 2014 06:57:59 -0500 Received: from linux.omap.com (dlelxs01.itg.ti.com [157.170.227.31]) by dflp33.itg.ti.com (8.14.3/8.13.8) with ESMTP id s2HBvwOI007494; Mon, 17 Mar 2014 06:57:58 -0500 Received: from linux.omap.com (localhost [127.0.0.1]) by linux.omap.com (Postfix) with ESMTP id 7CB8980627; Mon, 17 Mar 2014 05:57:58 -0600 (CST) X-Original-To: davinci-linux-open-source@linux.davincidsp.com Delivered-To: davinci-linux-open-source@linux.davincidsp.com Received: from dflxv15.itg.ti.com (dflxv15.itg.ti.com [128.247.5.124]) by linux.omap.com (Postfix) with ESMTP id CDF6A80626 for ; Mon, 17 Mar 2014 05:57:53 -0600 (CST) Received: from DFLE72.ent.ti.com (dfle72.ent.ti.com [128.247.5.109]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id s2HBvrQs021740; Mon, 17 Mar 2014 06:57:53 -0500 Received: from dflp32.itg.ti.com (10.64.6.15) by DFLE72.ent.ti.com (128.247.5.109) with Microsoft SMTP Server id 14.3.174.1; Mon, 17 Mar 2014 06:57:53 -0500 Received: from psplinux063 (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp32.itg.ti.com (8.14.3/8.13.8) with ESMTP id s2HBvqvj015559; Mon, 17 Mar 2014 06:57:53 -0500 Received: from a0875516 by psplinux063 with local (Exim 4.71) (envelope-from ) id 1WPWAy-0005yJ-3t; Mon, 17 Mar 2014 17:27:52 +0530 From: Sekhar Nori To: Dan Williams , Vinod Koul Subject: [PATCH] dma: edma: fix incorrect SG list handling Date: Mon, 17 Mar 2014 17:27:28 +0530 Message-ID: <1395057448-22904-1-git-send-email-nsekhar@ti.com> X-Mailer: git-send-email 1.7.10.1 MIME-Version: 1.0 CC: DMA Engine Mailing List , Joel Fernandes , Linux DaVinci Mailing List , Jon Ringle X-BeenThere: davinci-linux-open-source@linux.davincidsp.com X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: Errors-To: davinci-linux-open-source-bounces@linux.davincidsp.com X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, 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 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: # v3.12.x+ Cc: Joel Fernandes Reported-by: Jon Ringle Signed-off-by: Sekhar Nori Tested-by: Jon Ringle Acked-by: Joel Fernandes Tested-by: Alexander Holler --- Jon, can you please confirm this fixes the issue you reported? Joel, can you ack this please? In particular, I was not able to test with SG list greater than MAX_NR_SG. 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); } /*