From: David Henningsson <david.henningsson@canonical.com>
Date: Wed, 8 May 2013 13:33:11 +0000 (+0200)
Subject: ALSA: Add comment for control TLV API
X-Git-Tag: v5.15~20114^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d24f5a9ad9febffa53b1d3fcdf36c9a2283d848e;p=platform%2Fkernel%2Flinux-starfive.git

ALSA: Add comment for control TLV API

Userspace is not meant to have to handle all strange dB ranges,
so add a specification comment.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

diff --git a/include/sound/tlv.h b/include/sound/tlv.h
index 28c65e1..e11e179 100644
--- a/include/sound/tlv.h
+++ b/include/sound/tlv.h
@@ -74,7 +74,11 @@
 #define DECLARE_TLV_DB_LINEAR(name, min_dB, max_dB)	\
 	unsigned int name[] = { TLV_DB_LINEAR_ITEM(min_dB, max_dB) }
 
-/* dB range container */
+/* dB range container:
+ * Items in dB range container must be ordered by their values and by their
+ * dB values. This implies that larger values must correspond with larger
+ * dB values (which is also required for all other mixer controls).
+ */
 /* Each item is: <min> <max> <TLV> */
 #define TLV_DB_RANGE_ITEM(...) \
 	TLV_ITEM(SNDRV_CTL_TLVT_DB_RANGE, __VA_ARGS__)