On Wed, Dec 23, 2020 at 08:09:41AM +0100, Takashi Iwai wrote:
On Wed, 23 Dec 2020 03:17:00 +0100,
Sasha Levin wrote:
From: Takashi Iwai <tiwai@xxxxxxx>
[ Upstream commit 93db51d06b32227319dae2ac289029ccf1b33181 ]
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@xxxxxxxx>
Tested-by: Keith Milner <kamilner@xxxxxxxxxxxxxxx>
Tested-by: Dylan Robinson <dylan_robinson@xxxxxxxx>
BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1178203
Link: https://lore.kernel.org/r/20201123085347.19667-4-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Please drop this for 5.4 or older. At least this caused some problem
on 5.3 kernel that confused USB core by some reason while it works
fine with the recent upstream.
Will do, thanks.
--
Thanks,
Sasha
