From patchwork Sun Jul 21 06:58:35 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 2830887 Return-Path: X-Original-To: patchwork-linux-omap@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 D5671C0319 for ; Sun, 21 Jul 2013 06:59:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F305620169 for ; Sun, 21 Jul 2013 06:59:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F1092015E for ; Sun, 21 Jul 2013 06:59:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752409Ab3GUG7N (ORCPT ); Sun, 21 Jul 2013 02:59:13 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:40096 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753503Ab3GUG7K (ORCPT ); Sun, 21 Jul 2013 02:59:10 -0400 Received: from dlelxv90.itg.ti.com ([172.17.2.17]) by devils.ext.ti.com (8.13.7/8.13.7) with ESMTP id r6L6wciK022487; Sun, 21 Jul 2013 01:58:38 -0500 Received: from DLEE70.ent.ti.com (dlee70.ent.ti.com [157.170.170.113]) by dlelxv90.itg.ti.com (8.14.3/8.13.8) with ESMTP id r6L6wbcV000442; Sun, 21 Jul 2013 01:58:38 -0500 Received: from dlelxv22.itg.ti.com (172.17.1.197) by DLEE70.ent.ti.com (157.170.170.113) with Microsoft SMTP Server id 14.2.342.3; Sun, 21 Jul 2013 01:58:37 -0500 Received: from joel-laptop.itg.ti.com (h56-25.vpn.ti.com [172.24.56.25]) by dlelxv22.itg.ti.com (8.13.8/8.13.8) with ESMTP id r6L6wZ7i011795; Sun, 21 Jul 2013 01:58:37 -0500 From: Joel Fernandes To: Tony Lindgren , Sekhar Nori , Santosh Shilimkar , Sricharan R , Rajendra Nayak , Lokesh Vutla , Matt Porter , Grant Likely , Rob Herring , Vinod Koul , Dan Williams , Mark Brown , Benoit Cousson , Russell King , Arnd Bergmann , Balaji TK , Gururaja Hebbar , Chris Ball , Jason Kridner CC: Linux OMAP List , Linux ARM Kernel List , Linux DaVinci Kernel List , Linux Kernel Mailing List , Linux MMC List , Joel Fernandes Subject: [RFC 4/5] dma: edma: Find missed events and issue them Date: Sun, 21 Jul 2013 01:58:35 -0500 Message-ID: <1374389915-32630-1-git-send-email-joelf@ti.com> X-Mailer: git-send-email 1.7.9.5 MIME-Version: 1.0 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Spam-Status: No, score=-8.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, 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 In an effort to move to using Scatter gather lists of any size with EDMA as discussed at [1] instead of placing limitations on the driver, we work through the limitations of the EDMAC hardware to find missed events and issue them. The sequence of events that require this are: For the scenario where MAX slots for an EDMA channel is 3: SG1 -> SG2 -> SG3 -> SG4 -> SG5 -> SG6 -> Null The above SG list will have to be DMA'd in 2 sets: (1) SG1 -> SG2 -> SG3 -> Null (2) SG4 -> SG5 -> SG6 -> Null After (1) is succesfully transferred, the events from the MMC controller donot stop coming and are missed by the time we have setup the transfer for (2). So here, we catch the events missed as an error condition and issue them manually. [1] http://marc.info/?l=linux-omap&m=137416733628831&w=2 Signed-off-by: Joel Fernandes --- drivers/dma/edma.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 0e7ed79..b0b5bcd 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -414,7 +414,15 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data) break; case DMA_CC_ERROR: - dev_dbg(dev, "transfer error on channel %d\n", ch_num); + if (echan->edesc) { + dev_dbg(dev, "Missed event on %d, retrying\n", + ch_num); + edma_clean_channel(echan->ch_num); + edma_stop(echan->ch_num); + edma_start(echan->ch_num); + edma_manual_trigger(echan->ch_num); + } + dev_dbg(dev, "handled error on channel %d\n", ch_num); break; default: break;