target/linux/brcm2708/patches-4.9/0121-bcm2835-i2s-Changes-for-allowing-asymmetric-sample-f.patch

   1 From 425ee76116894c97d5d97ad4883eb2612b8692f3 Mon Sep 17 00:00:00 2001
   2 From: Giedrius Trainavicius <giedrius@blokas.io>
   3 Date: Sun, 8 Jan 2017 15:58:54 +0200
   4 Subject: [PATCH] bcm2835-i2s: Changes for allowing asymmetric sample formats.
   5
   6 This is achieved by making changes only to the requested
   7 stream direction format, keeping the other stream direction
   8 configuration intact.
   9
  10 Signed-off-by: Giedrius Trainavicius <giedrius@blokas.io>
  11 ---
  12  sound/soc/bcm/bcm2835-i2s.c | 54 +++++++++++++++++++++++++++++++--------------
  13  1 file changed, 38 insertions(+), 16 deletions(-)
  14
  15 --- a/sound/soc/bcm/bcm2835-i2s.c
  16 +++ b/sound/soc/bcm/bcm2835-i2s.c
  17 @@ -237,7 +237,9 @@ static int bcm2835_i2s_hw_params(struct
  18         unsigned int sampling_rate = params_rate(params);
  19         unsigned int data_length, data_delay, bclk_ratio;
  20         unsigned int ch1pos, ch2pos, mode, format;
  21 +       unsigned int previous_ftxp, previous_frxp;
  22         uint32_t csreg;
  23 +       bool packed;
  24
  25         /*
  26          * If a stream is already enabled,
  27 @@ -320,26 +322,46 @@ static int bcm2835_i2s_hw_params(struct
  28                 return -EINVAL;
  29         }
  30
  31 -       /*
  32 -        * Set format for both streams.
  33 -        * We cannot set another frame length
  34 -        * (and therefore word length) anyway,
  35 -        * so the format will be the same.
  36 -        */
  37 -       regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG, format);
  38 -       regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG, format);
  39 +       /* Set the format for the matching stream direction. */
  40 +       switch (substream->stream) {
  41 +       case SNDRV_PCM_STREAM_PLAYBACK:
  42 +               regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG, format);
  43 +               break;
  44 +       case SNDRV_PCM_STREAM_CAPTURE:
  45 +               regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG, format);
  46 +               break;
  47 +       default:
  48 +               return -EINVAL;
  49 +       }
  50
  51         /* Setup the I2S mode */
  52 +       /* Keep existing FTXP and FRXP values. */
  53 +       regmap_read(dev->i2s_regmap, BCM2835_I2S_MODE_A_REG, &mode);
  54 +
  55 +       previous_ftxp = mode & BCM2835_I2S_FTXP;
  56 +       previous_frxp = mode & BCM2835_I2S_FRXP;
  57 +
  58         mode = 0;
  59
  60 -       if (data_length <= 16) {
  61 -               /*
  62 -                * Use frame packed mode (2 channels per 32 bit word)
  63 -                * We cannot set another frame length in the second stream
  64 -                * (and therefore word length) anyway,
  65 -                * so the format will be the same.
  66 -                */
  67 -               mode |= BCM2835_I2S_FTXP | BCM2835_I2S_FRXP;
  68 +       /*
  69 +        * Retain the frame packed mode (2 channels per 32 bit word)
  70 +        * of the other direction stream intact. The formats of each
  71 +        * direction can be different as long as the frame length is
  72 +        * shared for both.
  73 +        */
  74 +       packed = data_length <= 16;
  75 +
  76 +       switch (substream->stream) {
  77 +       case SNDRV_PCM_STREAM_PLAYBACK:
  78 +               mode |= previous_frxp;
  79 +               mode |= packed ? BCM2835_I2S_FTXP : 0;
  80 +               break;
  81 +       case SNDRV_PCM_STREAM_CAPTURE:
  82 +               mode |= previous_ftxp;
  83 +               mode |= packed ? BCM2835_I2S_FRXP : 0;
  84 +               break;
  85 +       default:
  86 +               return -EINVAL;
  87         }
  88
  89         mode |= BCM2835_I2S_FLEN(bclk_ratio - 1);