On Mon, Apr 25, 2016 at 03:54:18PM +0200, Lars-Peter Clausen wrote:
On 04/25/2016 03:39 PM, kernel@martin.sperl.org wrote:
From: Matthias Reichl hias@horus.com
Register i2s also as pcm device.
This is not really what this patch does.
Agreed, we need a better description.
Code ported from bcm2708-i2s driver in Raspberry Pi tree.
Signed-off-by: Florian Meier florian.meier@koalo.de Signed-off-by: Matthias Reichl hias@horus.com Signed-off-by: Martin Sperl kernel@martin.sperl.org
sound/soc/bcm/bcm2835-i2s.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c index a0026e2..8e93295 100644 --- a/sound/soc/bcm/bcm2835-i2s.c +++ b/sound/soc/bcm/bcm2835-i2s.c @@ -632,6 +632,27 @@ static const struct snd_soc_component_driver bcm2835_i2s_component = { .name = "bcm2835-i2s-comp", };
+static const struct snd_pcm_hardware bcm2835_pcm_hardware = {
- .info = SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_JOINT_DUPLEX |SNDRV_PCM_INFO_MMAP |SNDRV_PCM_INFO_MMAP_VALID,- .formats = SNDRV_PCM_FMTBIT_S16_LE |
SNDRV_PCM_FMTBIT_S24_LE |SNDRV_PCM_FMTBIT_S32_LE,- .period_bytes_min = 32,
- .period_bytes_max = 64 * PAGE_SIZE,
I think it'd be better to use SZ constants instead of x * PAGE_SIZE.
- .periods_min = 2,
- .periods_max = 255,
- .buffer_bytes_max = 128 * PAGE_SIZE,
+};
+static const struct snd_dmaengine_pcm_config bcm2835_dmaengine_pcm_config = {
- .prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config,
- .pcm_hardware = &bcm2835_pcm_hardware,
- .prealloc_buffer_size = 256 * PAGE_SIZE,
+};
The generic dmaengine PCM driver auto-discovers these things, no need to provide them. The code is OK as it is.
With the auto-discover code we loose the S16_LE format.
If I understood the code in dmaengine_pcm_set_runtime_hwparams correctly, this is because the DMA controller doesn't support 16bit transfers (only multiples of 32bit are allowed).
But since the I2S driver needs exactly 2 channels S16_LE actually works fine (one 32bit transfer per frame).
Do you know of a better way to get S16_LE support? It could well be that I missed something important...
static int bcm2835_i2s_probe(struct platform_device *pdev) { struct bcm2835_i2s_dev *dev; @@ -704,7 +725,9 @@ static int bcm2835_i2s_probe(struct platform_device *pdev) return ret; }
- ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, 0);
- ret = devm_snd_dmaengine_pcm_register(
&pdev->dev, &bcm2835_dmaengine_pcm_config,SND_DMAENGINE_PCM_FLAG_COMPAT);