[alsa-devel] [PATCH] [v2] ASoC: support all possible sample rates in the WM8776 driver

[Timur Tabi]

The .set_sysclk() function in ASoC codec drivers can be used to tell the
driver what the frequency of master clock (mclk) is.  Some codecs use a
divider on this clock to determine the sample rate.  The WM8776 is one such
codec.

So instead of hard-coding a list of specific sample rates supported, these
codec drivers can specify SNDRV_PCM_RATE_CONTINUOUS instead, clamping the
range to the absolute limits of the hardware.  Then the .hw_params() function
can use the mclk rate to determine whether any requested rate is actually
supported.

Although the WM8776 driver includes a .set_sysclk function, it was also
hard-coding the list of supported sample rates.  We change the hard-coded
list to a range within the capabilities of the WM8776 itself.

Signed-off-by: Timur Tabi <timur at freescale.com>
---
 sound/soc/codecs/wm8776.c |   13 ++++++-------
 1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/wm8776.c b/sound/soc/codecs/wm8776.c
index ad6f0fa..ca8a593 100644
--- a/sound/soc/codecs/wm8776.c
+++ b/sound/soc/codecs/wm8776.c
@@ -321,11 +321,6 @@ static int wm8776_set_bias_level(struct snd_soc_codec *codec,
 	return 0;
 }
 
-#define WM8776_RATES (SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 |\
-		      SNDRV_PCM_RATE_48000 | SNDRV_PCM_RATE_88200 |\
-		      SNDRV_PCM_RATE_96000)
-
-
 #define WM8776_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE |\
 			SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S32_LE)
 
@@ -350,7 +345,9 @@ static struct snd_soc_dai_driver wm8776_dai[] = {
 			.stream_name = "Playback",
 			.channels_min = 2,
 			.channels_max = 2,
-			.rates = WM8776_RATES,
+			.rates = SNDRV_PCM_RATE_CONTINUOUS,
+			.rate_min = 32000,
+			.rate_max = 192000,
 			.formats = WM8776_FORMATS,
 		},
 		.ops = &wm8776_dac_ops,
@@ -362,7 +359,9 @@ static struct snd_soc_dai_driver wm8776_dai[] = {
 			.stream_name = "Capture",
 			.channels_min = 2,
 			.channels_max = 2,
-			.rates = WM8776_RATES,
+			.rates = SNDRV_PCM_RATE_CONTINUOUS,
+			.rate_min = 32000,
+			.rate_max = 96000,
 			.formats = WM8776_FORMATS,
 		},
 		.ops = &wm8776_adc_ops,
-- 
1.7.3.4