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| author | Takashi Iwai <tiwai@suse.de> | 2020-11-23 11:53:09 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2020-11-23 17:11:33 +0300 |
| commit | 93db51d06b32227319dae2ac289029ccf1b33181 (patch) | |
| tree | f66f2c07fbb7b653c4abe410fb1c2b186247133f /sound/usb/clock.h | |
| parent | 4974b7950929e4a28d4eaee48e4ad07f168ac132 (diff) | |
| download | linux-93db51d06b32227319dae2ac289029ccf1b33181.tar.xz | |
ALSA: usb-audio: Check valid altsetting at parsing rates for UAC2/3
The current driver code assumes blindly that all found sample rates for
the same endpoint from the UAC2 and UAC3 descriptors can be used no
matter which altsetting, but actually this was wrong: some devices
accept only limited sample rates in each altsetting. For determining
which altsetting supports which rate, we need to verify each sample rate
and check the validity via UAC2_AS_VAL_ALT_SETTINGS. This control
reports back the available altsettings as a bitmap.
This patch implements the missing piece above, the verification and
reconstructs the sample rate tables based on the result.
An open question is how to deal with the altsettings that ended up
with no valid sample rates after verification. At least, there is a
device that showed this problem although the sample rates did work in
the later usage (see bug link). For now, we accept such an altset as
is, assuming that it's a firmware bug.
Reported-by: Dylan Robinson <dylan_robinson@motu.com>
Tested-by: Keith Milner <kamilner@superlative.org>
Tested-by: Dylan Robinson <dylan_robinson@motu.com>
BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1178203
Link: https://lore.kernel.org/r/20201123085347.19667-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb/clock.h')
| -rw-r--r-- | sound/usb/clock.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/usb/clock.h b/sound/usb/clock.h index 68df0fbe09d0..97597f5a3c18 100644 --- a/sound/usb/clock.h +++ b/sound/usb/clock.h @@ -9,4 +9,8 @@ int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface, int snd_usb_clock_find_source(struct snd_usb_audio *chip, struct audioformat *fmt, bool validate); +int snd_usb_set_sample_rate_v2v3(struct snd_usb_audio *chip, + const struct audioformat *fmt, + int clock, int rate); + #endif /* __USBAUDIO_CLOCK_H */ |