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| author | Pawel Moll <mail@pawelmoll.com> | 2013-02-21 01:55:50 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-28 06:59:02 -0800 |
| commit | e32afc122e3a808944a9f7af5612bf2a3cbea89a (patch) | |
| tree | 8718795508df5c4fa7fa206900fc918b50cdd294 | |
| parent | e3fc3cb2a03623b48250dd3a12378a42d276f20e (diff) | |
| download | lwn-e32afc122e3a808944a9f7af5612bf2a3cbea89a.tar.gz lwn-e32afc122e3a808944a9f7af5612bf2a3cbea89a.zip | |
ALSA: usb: Fix Processing Unit Descriptor parsers
commit b531f81b0d70ffbe8d70500512483227cc532608 upstream.
Commit 99fc86450c439039d2ef88d06b222fd51a779176 "ALSA: usb-mixer:
parse descriptors with structs" introduced a set of useful parsers
for descriptors. Unfortunately the parses for the Processing Unit
Descriptor came with a very subtle bug...
Functions uac_processing_unit_iProcessing() and
uac_processing_unit_specific() were indexing the baSourceID array
forgetting the fields before the iProcessing and process-specific
descriptors.
The problem was observed with Sound Blaster Extigy mixer,
where nNrModes in Up/Down-mix Processing Unit Descriptor
was accessed at offset 10 of the descriptor (value 0)
instead of offset 15 (value 7). In result the resulting
control had interesting limit values:
Simple mixer control 'Channel Routing Mode Select',0
Capabilities: volume volume-joined penum
Playback channels: Mono
Capture channels: Mono
Limits: 0 - -1
Mono: -1 [100%]
Fixed by starting from the bmControls, which was calculated
correctly, instead of baSourceID.
Now the mentioned control is fine:
Simple mixer control 'Channel Routing Mode Select',0
Capabilities: volume volume-joined penum
Playback channels: Mono
Capture channels: Mono
Limits: 0 - 6
Mono: 0 [0%]
Signed-off-by: Pawel Moll <mail@pawelmoll.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/usb/audio.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/usb/audio.h b/include/linux/usb/audio.h index a54b8255d75f..6f8b026b3396 100644 --- a/include/linux/usb/audio.h +++ b/include/linux/usb/audio.h @@ -384,14 +384,16 @@ static inline __u8 uac_processing_unit_iProcessing(struct uac_processing_unit_de int protocol) { __u8 control_size = uac_processing_unit_bControlSize(desc, protocol); - return desc->baSourceID[desc->bNrInPins + control_size]; + return *(uac_processing_unit_bmControls(desc, protocol) + + control_size); } static inline __u8 *uac_processing_unit_specific(struct uac_processing_unit_descriptor *desc, int protocol) { __u8 control_size = uac_processing_unit_bControlSize(desc, protocol); - return &desc->baSourceID[desc->bNrInPins + control_size + 1]; + return uac_processing_unit_bmControls(desc, protocol) + + control_size + 1; } /* 4.5.2 Class-Specific AS Interface Descriptor */ |