From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sriram Periyasamy Subject: [PATCH 2/4] ALSA: hda: Make sure DMA is started by reading back the RUN bit Date: Tue, 15 May 2018 12:10:54 +0530 Message-ID: <1526366456-20470-3-git-send-email-sriramx.periyasamy@intel.com> References: <1526366456-20470-1-git-send-email-sriramx.periyasamy@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by alsa0.perex.cz (Postfix) with ESMTP id 28629266F69 for ; Tue, 15 May 2018 08:51:20 +0200 (CEST) In-Reply-To: <1526366456-20470-1-git-send-email-sriramx.periyasamy@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: ALSA ML , Mark Brown Cc: Takashi Iwai , Liam Girdwood , Sriram Periyasamy , Pardha Saradhi K , Patches Audio List-Id: alsa-devel@alsa-project.org From: Pardha Saradhi K As per HW recommendation, after setting the RUN bit, software must read a 1 from the RUN bit, before modifying related control registers/re-starting the DMA engine. Signed-off-by: Pardha Saradhi K Signed-off-by: Sriram Periyasamy --- sound/hda/hdac_stream.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c index 2000ea6f48fa..33c8ced528f6 100644 --- a/sound/hda/hdac_stream.c +++ b/sound/hda/hdac_stream.c @@ -48,6 +48,8 @@ EXPORT_SYMBOL_GPL(snd_hdac_stream_init); void snd_hdac_stream_start(struct hdac_stream *azx_dev, bool fresh_start) { struct hdac_bus *bus = azx_dev->bus; + int timeout = 300; + unsigned char val; trace_snd_hdac_stream_start(bus, azx_dev); @@ -60,6 +62,20 @@ void snd_hdac_stream_start(struct hdac_stream *azx_dev, bool fresh_start) /* set DMA start and interrupt mask */ snd_hdac_stream_updateb(azx_dev, SD_CTL, 0, SD_CTL_DMA_START | SD_INT_MASK); + + do { + udelay(3); + val = snd_hdac_stream_readb(azx_dev, SD_CTL) & SD_CTL_DMA_START; + if (val) + break; + } while (--timeout); + + if (!timeout) { + azx_dev->running = false; + dev_err(azx_dev->bus->dev, "unable to start the stream\n"); + return; + } + azx_dev->running = true; } EXPORT_SYMBOL_GPL(snd_hdac_stream_start); -- 2.7.4