[ALSA] snd-emu10k1: Add a comment explaining the conversion function for dB gain.

Signed-off-by: James Courtier-Dutton <James@superbug.co.uk>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

diff --git a/sound/pci/emu10k1/emufx.c b/sound/pci/emu10k1/emufx.c
index 00fc904c251dc335fc77c87b845eb0efde703cd6..13cd6ce898115171b903283674c90425357b984d 100644 (file)
--- a/sound/pci/emu10k1/emufx.c
+++ b/sound/pci/emu10k1/emufx.c
@@ -267,6 +267,7 @@ static const u32 treble_table[41][5] = {
        { 0x37c4448b, 0xa45ef51d, 0x262f3267, 0x081e36dc, 0xfd8f5d14 }
 };
 
+/* dB gain = (float) 20 * log10( float(db_table_value) / 0x8000000 ) */
 static const u32 db_table[101] = {
        0x00000000, 0x01571f82, 0x01674b41, 0x01783a1b, 0x0189f540,
        0x019c8651, 0x01aff763, 0x01c45306, 0x01d9a446, 0x01eff6b8,