From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21552C31E4B for ; Fri, 14 Jun 2019 19:43:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3BD32183E for ; Fri, 14 Jun 2019 19:43:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560541409; bh=7gKmgo1dRjA4yONDe3HR3+7X4u/83d+VuGOw5pQZNh4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=H4l+zOrAgt/yb45hFXxduc7EWcMt/D4eogQ8Lu8QYHkES96Z4CDvBMcvdptytGPIR G0j+031El07S9riPElXbHiK6luA3XPVwk5eImGede3pTcoG+ayrKBQnX2IXtipIwJW Z7bonR4K6ucNmdYSQYDsMMPjcUEuhJ2km2fr4S3A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726072AbfFNTnY (ORCPT ); Fri, 14 Jun 2019 15:43:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:60546 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbfFNTnY (ORCPT ); Fri, 14 Jun 2019 15:43:24 -0400 Received: from localhost (107-207-74-175.lightspeed.austtx.sbcglobal.net [107.207.74.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C48B1217D6; Fri, 14 Jun 2019 19:43:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560541404; bh=7gKmgo1dRjA4yONDe3HR3+7X4u/83d+VuGOw5pQZNh4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Nx3YHCMvLrQ8EeCL7b6r55mXR4P7IXZevBKUROMh95rXS6UY1DZ8FLy1Vd88fYM3m 1jMsa1Si3koPI+t9iYqmsXLChMVRR0RV7IE0TaLzO0h0cZGiBV5Opyj0XjszVQqv62 Ovs6aoJfrjC36wQUiR4GhiihU0wad+USGgz1Xhvg= Date: Fri, 14 Jun 2019 14:43:22 -0500 From: Andy Gross To: Srinivas Kandagatla Cc: vkoul@kernel.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, sricharan@codeaurora.org Subject: Re: [PATCH] dmaengine: qcom-bam: fix circular buffer handling Message-ID: <20190614194322.GA4791@hector.attlocal.net> References: <20190614142012.31384-1-srinivas.kandagatla@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190614142012.31384-1-srinivas.kandagatla@linaro.org> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Fri, Jun 14, 2019 at 03:20:12PM +0100, Srinivas Kandagatla wrote: > For some reason arguments to most of the circular buffers > macros are used in reverse, tail is used for head and vice versa. > > This leads to bam thinking that there is an extra descriptor at the > end and leading to retransmitting descriptor which was not scheduled > by any driver. This happens after MAX_DESCRIPTORS (4096) are scheduled > and done, so most of the drivers would not notice this, unless they are > heavily using bam dma. Originally found this issue while testing > SoundWire over SlimBus on DB845c which uses DMA very heavily for > read/writes. > > Signed-off-by: Srinivas Kandagatla Reviewed-by: Andy Gross