From patchwork Thu Sep 26 15:06:35 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Pargmann X-Patchwork-Id: 2949151 Return-Path: X-Original-To: patchwork-linux-arm@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 51BC99F288 for ; Thu, 26 Sep 2013 15:07:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2B5AC202FF for ; Thu, 26 Sep 2013 15:07:40 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 624B1202FE for ; Thu, 26 Sep 2013 15:07:34 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VPDA6-0002nz-2N; Thu, 26 Sep 2013 15:07:26 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VPD9u-0001ED-Um; Thu, 26 Sep 2013 15:07:14 +0000 Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VPD9q-0001D3-Ox for linux-arm-kernel@lists.infradead.org; Thu, 26 Sep 2013 15:07:12 +0000 Received: from dude.hi.pengutronix.de ([2001:6f8:1178:2:21e:67ff:fe11:9c5c]) by metis.ext.pengutronix.de with esmtp (Exim 4.72) (envelope-from ) id 1VPD9P-0005qG-EV; Thu, 26 Sep 2013 17:06:43 +0200 Received: from mpa by dude.hi.pengutronix.de with local (Exim 4.80) (envelope-from ) id 1VPD9O-0007vI-DT; Thu, 26 Sep 2013 17:06:42 +0200 From: Markus Pargmann To: Vinod Koul Subject: [PATCH 2/3] dma: mxs-dma: Track number of irqs for callback Date: Thu, 26 Sep 2013 17:06:35 +0200 Message-Id: <1380207996-27257-3-git-send-email-mpa@pengutronix.de> X-Mailer: git-send-email 1.8.4.rc3 In-Reply-To: <1380207996-27257-1-git-send-email-mpa@pengutronix.de> References: <1380207996-27257-1-git-send-email-mpa@pengutronix.de> X-SA-Exim-Connect-IP: 2001:6f8:1178:2:21e:67ff:fe11:9c5c X-SA-Exim-Mail-From: mpa@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130926_110711_252296_8FEC24BB X-CRM114-Status: GOOD ( 18.21 ) X-Spam-Score: -4.3 (----) Cc: Markus Pargmann , kernel@pengutronix.de, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, 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 Currently there is one tasklet scheduled for all interrupts between two mxs_dma_tasklet calls for one channel. With more than one interrupts, the tasklet is only called once. Using low latency audio playback, can lead to problems. When using sound/soc/soc-dmaengine-pcm.c, the dmaengine_pcm_dma_complete relies on being called for each interrupt that occures. This function is the callback which is called from the mxs-dma driver in mxs_dma_tasklet. This can cause wrong position counters and can lead to a wrong DMA buffer offset. In this situation the DMA engine and pcm lib may write and read from the same buffer segment. This patch adds a locked per-channel irq counter and calls the callback function in a loop for irq-counter times. Signed-off-by: Markus Pargmann --- drivers/dma/mxs-dma.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c index bfca8dc..13c7d83 100644 --- a/drivers/dma/mxs-dma.c +++ b/drivers/dma/mxs-dma.c @@ -115,6 +115,8 @@ struct mxs_dma_chan { int desc_count; enum dma_status status; unsigned int flags; + unsigned int nr_irqs; + spinlock_t lock; #define MXS_DMA_SG_LOOP (1 << 0) }; @@ -267,9 +269,21 @@ static dma_cookie_t mxs_dma_tx_submit(struct dma_async_tx_descriptor *tx) static void mxs_dma_tasklet(unsigned long data) { struct mxs_dma_chan *mxs_chan = (struct mxs_dma_chan *) data; + unsigned long flags; + spin_lock_irqsave(&mxs_chan->lock, flags); + + /* + * Some DMA users need exactly one call for each interrupt generated. + * This loop calls the callback nr_irqs times. + */ if (mxs_chan->desc.callback) - mxs_chan->desc.callback(mxs_chan->desc.callback_param); + for (; mxs_chan->nr_irqs; --mxs_chan->nr_irqs) + mxs_chan->desc.callback(mxs_chan->desc.callback_param); + else + mxs_chan->nr_irqs = 0; + + spin_unlock_irqrestore(&mxs_chan->lock, flags); } static int mxs_dma_irq_to_chan(struct mxs_dma_engine *mxs_dma, int irq) @@ -290,6 +304,7 @@ static irqreturn_t mxs_dma_int_handler(int irq, void *dev_id) u32 completed; u32 err; int chan = mxs_dma_irq_to_chan(mxs_dma, irq); + unsigned long flags; if (chan < 0) return IRQ_NONE; @@ -344,6 +359,13 @@ static irqreturn_t mxs_dma_int_handler(int irq, void *dev_id) if (mxs_chan->status == DMA_SUCCESS) dma_cookie_complete(&mxs_chan->desc); + /* + * Increase the number of irqs we saw for this channel. + */ + spin_lock_irqsave(&mxs_chan->lock, flags); + ++mxs_chan->nr_irqs; + spin_unlock_irqrestore(&mxs_chan->lock, flags); + /* schedule tasklet on this channel */ tasklet_schedule(&mxs_chan->tasklet); @@ -385,6 +407,8 @@ static int mxs_dma_alloc_chan_resources(struct dma_chan *chan) /* the descriptor is ready */ async_tx_ack(&mxs_chan->desc); + spin_lock_init(&mxs_chan->lock); + return 0; err_clk: