[PATCH] ALSA: pcm: One more dependency for hw constraints

[Takashi Iwai]

The fix for a long-standing USB-audio bug required one more dependency
variable to be added to the hw constraints.  Unfortunately I didn't
realize at debugging that the new addition may result in the overflow
of the dependency array of each snd_pcm_hw_rule (up to three plus a
sentinel), because USB-audio driver adds one more dependency only for
a certain device and bus, hence it works as is for many devices.  But
in a bad case, a simple open always results in -EINVAL (with kernel
WARNING if CONFIG_SND_DEBUG is set) no matter what is passed.

Since the dependencies are real and unavoidable (USB-audio restricts
the hw_params per looping over the format/rate/channels combos), the
only good solution seems to raise the bar for one more dependency for
snd_pcm_hw_rule -- so does this patch: now the hw constraint
dependencies can be up to four.

Fixes: 506c203cc3de ("ALSA: usb-audio: Fix hw constraints dependencies")
Reported-by: Jamie Heilman <jamie at audible.transient.net>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 include/sound/pcm.h     | 2 +-
 sound/core/pcm_native.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 2336bf9243e1..2e1200d17d0c 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -229,7 +229,7 @@ typedef int (*snd_pcm_hw_rule_func_t)(struct snd_pcm_hw_params *params,
 struct snd_pcm_hw_rule {
 	unsigned int cond;
 	int var;
-	int deps[4];
+	int deps[5];
 
 	snd_pcm_hw_rule_func_t func;
 	void *private;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 9f3f8e953ff0..c4aac703dc22 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -382,8 +382,8 @@ static int constrain_params_by_rules(struct snd_pcm_substream *substream,
 			continue;
 
 		/*
-		 * The 'deps' array includes maximum three dependencies
-		 * to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fourth
+		 * The 'deps' array includes maximum four dependencies
+		 * to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fifth
 		 * member of this array is a sentinel and should be
 		 * negative value.
 		 *
-- 
2.26.2