#713 emu10k1 mixer issue (5.1)

Hello,

There is a recurrent issue with emu10k1 when using
surround sound : the mixer mixes only front left and front
right, while the other (center and rear) remain unaffected.
(http://forums.gentoo.org/viewtopic-t-391429.html to point
one among several)

Here is my cat /proc/asound/card0/emu10k1 :

EMU10K1

Card : Creative
Internal TRAM (words) : 0x2000
External TRAM (words) : 0x8000

Effect Send Routing :
Ch0: A=0, B=1, C=2, D=3
Ch1: A=0, B=1, C=2, D=3
Ch2: A=0, B=1, C=2, D=3
Ch3: A=0, B=1, C=2, D=3
Ch4: A=0, B=1, C=2, D=3
Ch5: A=0, B=1, C=2, D=3
Ch6: A=0, B=1, C=2, D=3
Ch7: A=0, B=1, C=2, D=3
Ch8: A=0, B=1, C=2, D=3
Ch9: A=0, B=1, C=2, D=3
Ch10: A=0, B=1, C=2, D=3
Ch11: A=0, B=1, C=2, D=3
Ch12: A=0, B=1, C=2, D=3
Ch13: A=0, B=1, C=2, D=3
Ch14: A=0, B=1, C=2, D=3
Ch15: A=0, B=1, C=2, D=3
Ch16: A=0, B=1, C=2, D=3
Ch17: A=0, B=1, C=2, D=3
Ch18: A=0, B=1, C=2, D=3
Ch19: A=0, B=1, C=2, D=3
Ch20: A=0, B=1, C=2, D=3
Ch21: A=0, B=1, C=2, D=3
Ch22: A=0, B=1, C=2, D=3
Ch23: A=0, B=1, C=2, D=3
Ch24: A=0, B=1, C=2, D=3
Ch25: A=0, B=1, C=2, D=3
Ch26: A=0, B=1, C=2, D=3
Ch27: A=0, B=1, C=2, D=3
Ch28: A=0, B=1, C=2, D=3
Ch29: A=0, B=1, C=2, D=3
Ch30: A=0, B=1, C=2, D=3
Ch31: A=0, B=1, C=2, D=3
Ch32: A=0, B=1, C=2, D=3
Ch33: A=0, B=1, C=2, D=3
Ch34: A=0, B=1, C=2, D=3
Ch35: A=0, B=1, C=2, D=3
Ch36: A=0, B=1, C=2, D=3
Ch37: A=0, B=1, C=2, D=3
Ch38: A=0, B=1, C=2, D=3
Ch39: A=0, B=1, C=2, D=3
Ch40: A=0, B=1, C=2, D=3
Ch41: A=0, B=1, C=2, D=3
Ch42: A=0, B=1, C=2, D=3
Ch43: A=0, B=1, C=2, D=3
Ch44: A=0, B=1, C=2, D=3
Ch45: A=0, B=1, C=2, D=3
Ch46: A=0, B=1, C=2, D=3
Ch47: A=0, B=1, C=2, D=3
Ch48: A=0, B=1, C=2, D=3
Ch49: A=0, B=1, C=2, D=3
Ch50: A=0, B=1, C=2, D=3
Ch51: A=0, B=1, C=2, D=3
Ch52: A=0, B=1, C=2, D=3
Ch53: A=0, B=1, C=2, D=3
Ch54: A=0, B=1, C=2, D=3
Ch55: A=0, B=1, C=2, D=3
Ch56: A=0, B=1, C=2, D=3
Ch57: A=0, B=1, C=2, D=3
Ch58: A=0, B=1, C=2, D=3
Ch59: A=0, B=1, C=2, D=3
Ch60: A=0, B=1, C=2, D=3
Ch61: A=0, B=1, C=2, D=3
Ch62: A=0, B=1, C=2, D=3
Ch63: A=0, B=1, C=2, D=3

Captured FX Outputs :
Output 16 [???]
Output 17 [Analog Center]
Output 18 [Analog LFE]
Output 19 [???]
Output 20 [???]
Output 21 [???]
Output 22 [???]
Output 23 [???]
Output 24 [???]
Output 25 [???]
Output 26 [???]
Output 27 [???]
Output 28 [???]
Output 29 [???]
Output 30 [???]
Output 31 [???]

All FX Outputs :
Output 00 [AC97 Left]
Output 01 [AC97 Right]
Output 02 [Optical IEC958 Left]
Output 03 [Optical IEC958 Right]
Output 04 [Center]
Output 05 [LFE]
Output 06 [Headphone Left]
Output 07 [Headphone Right]
Output 08 [Surround Left]
Output 09 [Surround Right]
Output 10 [PCM Capture Left]
Output 11 [PCM Capture Right]
Output 12 [MIC Capture]
Output 13 [AC97 Surround Left]
Output 14 [AC97 Surround Right]
Output 15 [???]
Output 16 [???]
Output 17 [Analog Center]
Output 18 [Analog LFE]
Output 19 [???]
Output 20 [???]
Output 21 [???]
Output 22 [???]
Output 23 [???]
Output 24 [???]
Output 25 [???]
Output 26 [???]
Output 27 [???]
Output 28 [???]
Output 29 [???]
Output 30 [???]
Output 31 [???]