Re: [PATCH RFC v1 2/2] ASoC: meson: aiu: Move AIU_I2S_MISC hold setting to aiu-fifo-i2s

On Sun 05 Dec 2021 at 19:08, Martin Blumenstingl martin.blumenstingl@googlemail.com wrote:

The out-of-tree vendor driver uses the following approach to set the AIU_I2S_MISC register:

1. write AIU_MEM_I2S_START_PTR and AIU_MEM_I2S_RD_PTR
2. configure AIU_I2S_MUTE_SWAP[15:0]
3. write AIU_MEM_I2S_END_PTR
4. set AIU_I2S_MISC[2] to 1 (documented as: "put I2S interface in hold mode")
5. set AIU_I2S_MISC[4] to 1 (depending on the driver revision it always stays at 1 while for older drivers this bit is unset in step 4)
6. set AIU_I2S_MISC[2] to 0
7. write AIU_MEM_I2S_MASKS
8. toggle AIU_MEM_I2S_CONTROL[0]
9. toggle AIU_MEM_I2S_BUF_CNTL[0]

Additional testing shows that when AIU_I2S_MISC[2] is set to 1 then no interrupts are generated anymore. The way this bit is managed by the vendor driver as well as not getting any interrupts can mean that it's related to the FIFO and not the encoder.

Not necessarily. If the encoder stops pulling data, the FIFO will going over the DDR. Since it generates an IRQ after reading N bytes, IRQ would stop too. AFAIK, if the pipeline is stalled, the IRQ stops anyway

... but this is not really important

Move setting the AIU_I2S_MISC[2] bit to aiu_fifo_i2s_hw_params() so it closer resembles the flow in the vendor kernel. While here also configure AIU_I2S_MISC[4] (documented as: "force each audio data to left or right according to the bit attached with the audio data") similar to how the vendor driver does this.

I understand the part of HOLD, not about FORCE_LR. Is it necessary to fix the problem ? Have you tested without this change ?

This fixes the infamous and long-standing "machine gun noise" issue (a buffer underrun issue).

Well done ! It took us a while to nail it, Thanks a lot !!

Fixes: 6ae9ca9ce986bf ("ASoC: meson: aiu: add i2s and spdif support") Reported-by: Christian Hewitt christianshewitt@gmail.com Reported-by: Geraldo Nascimento geraldogabriel@gmail.com Signed-off-by: Martin Blumenstingl martin.blumenstingl@googlemail.com

---

sound/soc/meson/aiu-encoder-i2s.c | 33 ------------------------------- sound/soc/meson/aiu-fifo-i2s.c | 12 +++++++++++ 2 files changed, 12 insertions(+), 33 deletions(-)

diff --git a/sound/soc/meson/aiu-encoder-i2s.c b/sound/soc/meson/aiu-encoder-i2s.c index 932224552146..67729de41a73 100644 --- a/sound/soc/meson/aiu-encoder-i2s.c +++ b/sound/soc/meson/aiu-encoder-i2s.c @@ -18,7 +18,6 @@ #define AIU_RST_SOFT_I2S_FAST BIT(0)

#define AIU_I2S_DAC_CFG_MSB_FIRST BIT(2) -#define AIU_I2S_MISC_HOLD_EN BIT(2) #define AIU_CLK_CTRL_I2S_DIV_EN BIT(0) #define AIU_CLK_CTRL_I2S_DIV GENMASK(3, 2) #define AIU_CLK_CTRL_AOCLK_INVERT BIT(6) @@ -36,37 +35,6 @@ static void aiu_encoder_i2s_divider_enable(struct snd_soc_component *component, enable ? AIU_CLK_CTRL_I2S_DIV_EN : 0); }

-static void aiu_encoder_i2s_hold(struct snd_soc_component *component,

• 		 bool enable)
  

-{

• snd_soc_component_update_bits(component, AIU_I2S_MISC,

• 		      AIU_I2S_MISC_HOLD_EN,
  

• 		      enable ? AIU_I2S_MISC_HOLD_EN : 0);
  

-}

-static int aiu_encoder_i2s_trigger(struct snd_pcm_substream *substream, int cmd,

• 		   struct snd_soc_dai *dai)
  

-{

• struct snd_soc_component *component = dai->component;
• switch (cmd) {
• case SNDRV_PCM_TRIGGER_START:
• case SNDRV_PCM_TRIGGER_RESUME:
• case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:

• aiu_encoder_i2s_hold(component, false);
  

• return 0;
  

• case SNDRV_PCM_TRIGGER_STOP:
• case SNDRV_PCM_TRIGGER_SUSPEND:
• case SNDRV_PCM_TRIGGER_PAUSE_PUSH:

• aiu_encoder_i2s_hold(component, true);
  

• return 0;
  

• default:

• return -EINVAL;
  

• }

-}

static int aiu_encoder_i2s_setup_desc(struct snd_soc_component *component, struct snd_pcm_hw_params *params) { @@ -353,7 +321,6 @@ static void aiu_encoder_i2s_shutdown(struct snd_pcm_substream *substream, }

const struct snd_soc_dai_ops aiu_encoder_i2s_dai_ops = {

• .trigger = aiu_encoder_i2s_trigger, .hw_params = aiu_encoder_i2s_hw_params, .hw_free = aiu_encoder_i2s_hw_free, .set_fmt = aiu_encoder_i2s_set_fmt,

diff --git a/sound/soc/meson/aiu-fifo-i2s.c b/sound/soc/meson/aiu-fifo-i2s.c index 2388a2d0b3a6..d0a1090d6465 100644 --- a/sound/soc/meson/aiu-fifo-i2s.c +++ b/sound/soc/meson/aiu-fifo-i2s.c @@ -20,6 +20,8 @@ #define AIU_MEM_I2S_CONTROL_MODE_16BIT BIT(6) #define AIU_MEM_I2S_BUF_CNTL_INIT BIT(0) #define AIU_RST_SOFT_I2S_FAST BIT(0) +#define AIU_I2S_MISC_HOLD_EN BIT(2) +#define AIU_I2S_MISC_FORCE_LEFT_RIGHT BIT(4)

#define AIU_FIFO_I2S_BLOCK 256

@@ -90,6 +92,10 @@ static int aiu_fifo_i2s_hw_params(struct snd_pcm_substream *substream, unsigned int val; int ret;

• snd_soc_component_update_bits(component, AIU_I2S_MISC,

• 		      AIU_I2S_MISC_HOLD_EN,
  

• 		      AIU_I2S_MISC_HOLD_EN);
  

• ret = aiu_fifo_hw_params(substream, params, dai); if (ret) return ret;

@@ -117,6 +123,12 @@ static int aiu_fifo_i2s_hw_params(struct snd_pcm_substream *substream, snd_soc_component_update_bits(component, AIU_MEM_I2S_MASKS, AIU_MEM_I2S_MASKS_IRQ_BLOCK, val);

• snd_soc_component_update_bits(component, AIU_I2S_MISC,

• 		      AIU_I2S_MISC_FORCE_LEFT_RIGHT,
  

• 		      AIU_I2S_MISC_FORCE_LEFT_RIGHT);
  

If it is necessary, even if we don't really understand why, it is fine by me. But if it is not, I would prefer we leave it out of it, or at least, make it a separate patch.

• snd_soc_component_update_bits(component, AIU_I2S_MISC,

• 		      AIU_I2S_MISC_HOLD_EN, 0);
  

• return 0;

}