Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751537AbaLOIil (ORCPT ); Mon, 15 Dec 2014 03:38:41 -0500 Received: from fw-tnat.cambridge.arm.com ([217.140.96.140]:43721 "EHLO cam-smtp0.cambridge.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750836AbaLOIij (ORCPT ); Mon, 15 Dec 2014 03:38:39 -0500 Message-ID: <548E9DE0.7050502@arm.com> Date: Mon, 15 Dec 2014 08:37:52 +0000 From: Andrew Jackson User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Lars-Peter Clausen , Jaroslav Kysela , Takashi Iwai CC: Liam Girdwood , Mark Brown , Rajeev Kumar , Liviu Dudau , Arnd Bergmann , "linux-arm-kernel@lists.infradead.org" , "alsa-devel@alsa-project.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v2 2/6] ASoC: dwc: Ensure FIFOs are flushed to prevent channel swap References: <548AB75E.9030302@metafoo.de> In-Reply-To: <548AB75E.9030302@metafoo.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/14 09:37, Lars-Peter Clausen wrote: > On 12/12/2014 10:25 AM, Andrew Jackson wrote: >> From: Andrew Jackson >> >> If the FIFOs aren't flushed, the left/right channels may be swapped: >> this may occur if the FIFOs are not empty when the streams start. >> >> Signed-off-by: Andrew Jackson >> --- >> sound/soc/dwc/designware_i2s.c | 2 ++ >> 1 files changed, 2 insertions(+), 0 deletions(-) >> >> diff --git a/sound/soc/dwc/designware_i2s.c b/sound/soc/dwc/designware_i2s.c >> index ef771ea..b9d6a25 100644 >> --- a/sound/soc/dwc/designware_i2s.c >> +++ b/sound/soc/dwc/designware_i2s.c >> @@ -228,12 +228,14 @@ static int dw_i2s_hw_params(struct snd_pcm_substream *substream, >> i2s_disable_channels(dev, substream->stream); >> >> if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) { >> + i2s_write_reg(dev->i2s_base, TXFFR, 1); >> i2s_write_reg(dev->i2s_base, TCR(ch_reg), xfer_resolution); >> i2s_write_reg(dev->i2s_base, TFCR(ch_reg), 0x02); >> irq = i2s_read_reg(dev->i2s_base, IMR(ch_reg)); >> i2s_write_reg(dev->i2s_base, IMR(ch_reg), irq & ~0x30); >> i2s_write_reg(dev->i2s_base, TER(ch_reg), 1); >> } else { >> + i2s_write_reg(dev->i2s_base, RXFFR, 1); >> i2s_write_reg(dev->i2s_base, RCR(ch_reg), xfer_resolution); >> i2s_write_reg(dev->i2s_base, RFCR(ch_reg), 0x07); >> irq = i2s_read_reg(dev->i2s_base, IMR(ch_reg)); >> > > This should probably go into the prepare callback. prepare is for example > also called when recovering from a underrun/overrun. Whereas hwparams is > only called during initial setup of the stream. That's a good idea: thank you. I'll rework the patch with this in mind. Andrew -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/