From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: [PATCH] ASoC: sun8i-codec: Add a comment on the LRCK inversion Date: Thu, 9 Nov 2017 10:40:46 +0100 Message-ID: <20171109094046.13483-1-maxime.ripard@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.free-electrons.com (mail.free-electrons.com [62.4.15.54]) by alsa0.perex.cz (Postfix) with ESMTP id EA0702674B5 for ; Thu, 9 Nov 2017 10:40:58 +0100 (CET) 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: broonie@kernel.org, lgirdwood@gmail.com, Chen-Yu Tsai , Maxime Ripard Cc: alsa-devel@alsa-project.org, Mylene Josserand , linux-arm-kernel@lists.infradead.org List-Id: alsa-devel@alsa-project.org The current code might be a bit intriguing without having experienced the issue before, and might come up as a mistake. Make explicit what's going on by adding a comment. Signed-off-by: Maxime Ripard --- sound/soc/sunxi/sun8i-codec.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/sound/soc/sunxi/sun8i-codec.c b/sound/soc/sunxi/sun8i-codec.c index 7a312168f864..3dd183be08a4 100644 --- a/sound/soc/sunxi/sun8i-codec.c +++ b/sound/soc/sunxi/sun8i-codec.c @@ -198,6 +198,17 @@ static int sun8i_set_fmt(struct snd_soc_dai *dai, unsigned int fmt) regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL, BIT(SUN8I_AIF1CLK_CTRL_AIF1_BCLK_INV), value << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_INV); + + /* + * It appears that the DAI and the codec don't share the same + * polarity for the LRCK signal when they mean 'normal' and + * 'inverted' in the datasheet. + * + * Since the DAI here is our regular i2s driver that have been + * tested with way more codecs than just this one, it means + * that the codec probably gets it backward, and we have to + * invert the value here. + */ regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL, BIT(SUN8I_AIF1CLK_CTRL_AIF1_LRCK_INV), !value << SUN8I_AIF1CLK_CTRL_AIF1_LRCK_INV); -- 2.14.3