target/linux/brcm2708/patches-4.14/950-0161-ASoC-bcm2835-fix-hw_params-error-when-device-is-in-p.patch

   1 From 0f409e6c30a04eb85792a6883e81ad2af118c7bd Mon Sep 17 00:00:00 2001
   2 From: Matthias Reichl <github@hias.horus.com>
   3 Date: Thu, 18 Jan 2018 12:36:44 +0100
   4 Subject: [PATCH 161/454] ASoC: bcm2835: fix hw_params error when device is in
   5  prepared state (#2345)
   6
   7 commit 8d5737a5f53902a916ee1e1cb248c9b8b883b2ea  upstream.
   8
   9 If bcm2835 is configured as bitclock master calling hw_params()
  10 after prepare() fails with EBUSY. This also makes it impossible to
  11 use bcm2835 in full duplex mode.
  12
  13 The error is caused by the split clock setup: clk_set_rate
  14 is called in hw_params, clk_prepare_enable in prepare. As hw_params
  15 doesn't check if the clock was already enabled clk_set_rate
  16 fails with EBUSY.
  17
  18 Fix this by moving clock startup from prepare to hw_params and
  19 let hw_params properly deal with an already set up or enabled
  20 clock.
  21
  22 Signed-off-by: Matthias Reichl <hias@horus.com>
  23 ---
  24  sound/soc/bcm/bcm2835-i2s.c | 20 ++++++++++++++------
  25  1 file changed, 14 insertions(+), 6 deletions(-)
  26
  27 --- a/sound/soc/bcm/bcm2835-i2s.c
  28 +++ b/sound/soc/bcm/bcm2835-i2s.c
  29 @@ -130,6 +130,7 @@ struct bcm2835_i2s_dev {
  30         struct regmap                           *i2s_regmap;
  31         struct clk                              *clk;
  32         bool                                    clk_prepared;
  33 +       int                                     clk_rate;
  34  };
  35
  36  static void bcm2835_i2s_start_clock(struct bcm2835_i2s_dev *dev)
  37 @@ -419,10 +420,19 @@ static int bcm2835_i2s_hw_params(struct
  38         }
  39
  40         /* Clock should only be set up here if CPU is clock master */
  41 -       if (bit_clock_master) {
  42 -               ret = clk_set_rate(dev->clk, bclk_rate);
  43 -               if (ret)
  44 -                       return ret;
  45 +       if (bit_clock_master &&
  46 +           (!dev->clk_prepared || dev->clk_rate != bclk_rate)) {
  47 +               if (dev->clk_prepared)
  48 +                       bcm2835_i2s_stop_clock(dev);
  49 +
  50 +               if (dev->clk_rate != bclk_rate) {
  51 +                       ret = clk_set_rate(dev->clk, bclk_rate);
  52 +                       if (ret)
  53 +                               return ret;
  54 +                       dev->clk_rate = bclk_rate;
  55 +               }
  56 +
  57 +               bcm2835_i2s_start_clock(dev);
  58         }
  59
  60         /* Setup the frame format */
  61 @@ -618,8 +628,6 @@ static int bcm2835_i2s_prepare(struct sn
  62         struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
  63         uint32_t cs_reg;
  64
  65 -       bcm2835_i2s_start_clock(dev);
  66 -
  67         /*
  68          * Clear both FIFOs if the one that should be started
  69          * is not empty at the moment. This should only happen