From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751163AbcDPFOE (ORCPT ); Sat, 16 Apr 2016 01:14:04 -0400 Received: from mga02.intel.com ([134.134.136.20]:13468 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750947AbcDPFOD (ORCPT ); Sat, 16 Apr 2016 01:14:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,490,1455004800"; d="scan'208";a="959860935" Date: Sat, 16 Apr 2016 10:48:34 +0530 From: Vinod Koul To: Robert Jarzmik Cc: Daniel Mack , Haojian Zhuang , linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] dmaengine: pxa: handle bus errors Message-ID: <20160416051834.GY2274@localhost> References: <1459200744-13245-1-git-send-email-robert.jarzmik@free.fr> <20160413135324.GQ2274@localhost> <87k2k0t5gh.fsf@belgarion.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k2k0t5gh.fsf@belgarion.home> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 14, 2016 at 08:23:26PM +0200, Robert Jarzmik wrote: > Vinod Koul writes: > > > On Mon, Mar 28, 2016 at 11:32:24PM +0200, Robert Jarzmik wrote: > >> In the current state, upon bus error the driver will spin endlessly, > >> relaunching the last tx, which will fail again and again : > >> - a bus error happens > >> - pxad_chan_handler() is called > >> - as PXA_DCSR_STOPSTATE is true, the last non-terminated transaction is > >> lauched, which is the one triggering the bus error, as it didn't > >> terminate > >> - moreover, the STOP interrupt fires a new, as the STOPIRQEN is still > >> active > >> > >> Break this logic by stopping the automatic relaunch of a dma channel > >> upon a bus error, even if there are still pending issued requests on it. > >> > >> As dma_cookie_status() seems unable to return DMA_ERROR in its current > >> form, ie. there seems no way to mark a DMA_ERROR on a per-async-tx > >> basis, it is chosen in this patch to remember on the channel which > >> transaction failed, and report it in pxad_tx_status(). > >> > >> It's a bit misleading because if T1, T2, T3 and T4 were queued, and T1 > >> was completed while T2 causes a bus error, the status of T3 and T4 will > >> be reported as DMA_IN_PROGRESS, while the channel is actually stopped. > > > > No it is not misleading. The subsequent descriptor can be submitted and > > continued. But yes you are right on the error reporting part, that is > > something we need to add. > Ok, fair enough. > > > So what exactly are you trying to fix/achive here? > Euh you mean the first chapter about the "endless spin" is not clear ? > This is what I'm trying to fix, the unstoppable endless relauch of a descriptor > doomed to make the same bus error over and over again. Okay so IIUC the patch here essential stops all transfers and abort the channel, right? -- ~Vinod