From d5b702a64b4c273c8eed7e4e721364493d01fdc9 Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens@ladisch.de>
Date: Fri, 16 Sep 2011 23:03:02 +0200
Subject: ALSA: pcm: add snd_pcm_hw_rule_noresample()

Add a helper function to allow drivers to disable hardware resampling
when the application has specified the SNDRV_PCM_HW_PARAMS_NORESAMPLE
flag.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/pcm_lib.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'sound/core')

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 62e90b862a0d..95d1e789715f 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1399,6 +1399,32 @@ int snd_pcm_hw_constraint_pow2(struct snd_pcm_runtime *runtime,
 
 EXPORT_SYMBOL(snd_pcm_hw_constraint_pow2);
 
+static int snd_pcm_hw_rule_noresample_func(struct snd_pcm_hw_params *params,
+					   struct snd_pcm_hw_rule *rule)
+{
+	unsigned int base_rate = (unsigned int)(uintptr_t)rule->private;
+	struct snd_interval *rate;
+
+	rate = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+	return snd_interval_list(rate, 1, &base_rate, 0);
+}
+
+/**
+ * snd_pcm_hw_rule_noresample - add a rule to allow disabling hw resampling
+ * @runtime: PCM runtime instance
+ * @base_rate: the rate at which the hardware does not resample
+ */
+int snd_pcm_hw_rule_noresample(struct snd_pcm_runtime *runtime,
+			       unsigned int base_rate)
+{
+	return snd_pcm_hw_rule_add(runtime, SNDRV_PCM_HW_PARAMS_NORESAMPLE,
+				   SNDRV_PCM_HW_PARAM_RATE,
+				   snd_pcm_hw_rule_noresample_func,
+				   (void *)(uintptr_t)base_rate,
+				   SNDRV_PCM_HW_PARAM_RATE, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_rule_noresample);
+
 static void _snd_pcm_hw_param_any(struct snd_pcm_hw_params *params,
 				  snd_pcm_hw_param_t var)
 {
-- 
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