linux-kernel - [PATCH 2/2] ALSA: ASoc: davinci-mcasp: Add Support BCLK-to-LRCLK ratio for TDM modes

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Date:	Fri, 19 Apr 2013 15:28:44 +0200
From:	Michal Bachraty <michal.bachraty@...eamunlimited.com>
To:	perex@...ex.cz, tiwai@...e.de, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Cc:	broonie@...nsource.wolfsonmicro.com, lgirdwood@...il.com,
	marek.belisko@...eamunlimited.com,
	Michal Bachraty <michal.bachraty@...eamunlimited.com>
Subject: [PATCH 2/2] ALSA: ASoc: davinci-mcasp: Add Support BCLK-to-LRCLK ratio for TDM modes

For TDM mode, BCLK-to-LCLK ratio is computed as (tdm_slots) x (word_length).
I2S mode is only subset of TDM mode with specific tdm_slots = 2 channels.
Also bclk_lrclk_ratio can be greater than 255, therefore u16 need to be used.

Signed-off-by: Michal Bachraty <michal.bachraty@...eamunlimited.com>
---
 sound/soc/davinci/davinci-mcasp.c |    7 ++++---
 sound/soc/davinci/davinci-mcasp.h |    2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 63633e9..d54e0d9 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -636,11 +636,12 @@ static int davinci_config_channel_size(struct davinci_audio_dev *dev,
 	 * callback, take it into account here. That allows us to for example
 	 * send 32 bits per channel to the codec, while only 16 of them carry
 	 * audio payload.
-	 * The clock ratio is given for a full period of data (both left and
-	 * right channels), so it has to be divided by 2.
+	 * The clock ratio is given for a full period of data (for I2S format
+	 * both left and right channels), so it has to be divided by number of
+	 * tdm-slots (for I2S - divided by 2).
 	 */
 	if (dev->bclk_lrclk_ratio)
-		word_length = dev->bclk_lrclk_ratio / 2;
+		word_length = dev->bclk_lrclk_ratio / dev->tdm_slots;
 
 	/* mapping of the XSSZ bit-field as described in the datasheet */
 	fmt = (word_length >> 1) - 1;
diff --git a/sound/soc/davinci/davinci-mcasp.h b/sound/soc/davinci/davinci-mcasp.h
index 0edd3b5..a9ac0c1 100644
--- a/sound/soc/davinci/davinci-mcasp.h
+++ b/sound/soc/davinci/davinci-mcasp.h
@@ -38,7 +38,7 @@ struct davinci_audio_dev {
 	u8	num_serializer;
 	u8	*serial_dir;
 	u8	version;
-	u8	bclk_lrclk_ratio;
+	u16	bclk_lrclk_ratio;
 
 	/* McASP FIFO related */
 	u8	txnumevt;
-- 
1.7.9.5

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