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Trent Piepho df443aad51 Bluetooth: btusb: Always fallback to alt 1 for WBS
commit 517b693351a2d04f3af1fc0e506ac7e1346094de upstream.

When alt mode 6 is not available, fallback to the kernel <= 5.7 behavior
of always using alt mode 1.

Prior to kernel 5.8, btusb would always use alt mode 1 for WBS (Wide
Band Speech aka mSBC aka transparent SCO).  In commit baac6276c0
("Bluetooth: btusb: handle mSBC audio over USB Endpoints") this
was changed to use alt mode 6, which is the recommended mode in the
Bluetooth spec (Specifications of the Bluetooth System, v5.0, Vol 4.B
§2.2.1).  However, many if not most BT USB adapters do not support alt
mode 6.  In fact, I have been unable to find any which do.

In kernel 5.8, this was changed to use alt mode 6, and if not available,
use alt mode 0.  But mode 0 has a zero byte max packet length and can
not possibly work.  It is just there as a zero-bandwidth dummy mode to
work around a USB flaw that would prevent device enumeration if
insufficient bandwidth were available for the lowest isoc mode
supported.

In effect, WBS was broken for all USB-BT adapters that do not support
alt 6, which appears to nearly all of them.

Then in commit 461f95f04f ("Bluetooth: btusb: USB alternate setting 1 for
WBS") the 5.7 behavior was restored, but only for Realtek adapters.

I've tested a Broadcom BRCM20702A and CSR 8510 adapter, both work with
the 5.7 behavior and do not with the 5.8.

So get rid of the Realtek specific flag and use the 5.7 behavior for all
adapters as a fallback when alt 6 is not available.  This was the
kernel's behavior prior to 5.8 and I can find no adapters for which it
is not correct.  And even if there is an adapter for which this does not
work, the current behavior would be to fall back to alt 0, which can not
possibly work either, and so is no better.

Signed-off-by: Trent Piepho <tpiepho@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: Salvatore Bonaccorso <carnil@debian.org>
Cc: Sjoerd Simons <sjoerd@luon.net>
Cc: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-23 15:53:25 +01:00
arch xen/arm: don't ignore return errors from set_phys_to_machine 2021-02-23 15:53:24 +01:00
block bfq-iosched: Revert "bfq: Fix computation of shallow depth" 2021-02-17 11:02:24 +01:00
certs
crypto crypto: xor - Fix divide error in do_xor_speed() 2021-01-27 11:54:52 +01:00
Documentation ovl: implement volatile-specific fsync error behaviour 2021-02-10 09:29:16 +01:00
drivers Bluetooth: btusb: Always fallback to alt 1 for WBS 2021-02-23 15:53:25 +01:00
fs ovl: expand warning in ovl_d_real() 2021-02-17 11:02:30 +01:00
include Xen/gntdev: correct error checking in gntdev_map_grant_pages() 2021-02-23 15:53:24 +01:00
init fgraph: Initialize tracing_graph_pause at task creation 2021-02-10 09:29:16 +01:00
ipc
kernel bpf: Check for integer overflow when using roundup_pow_of_two() 2021-02-17 11:02:25 +01:00
lib udp: fix skb_copy_and_csum_datagram with odd segment sizes 2021-02-17 11:02:28 +01:00
LICENSES
mm Revert "mm: memcontrol: avoid workload stalls when lowering memory.high" 2021-02-13 13:55:17 +01:00
net net: fix proc_fs init handling in af_packet and tls 2021-02-23 15:53:23 +01:00
samples samples/bpf: Fix possible hang in xdpsock with multiple threads 2020-12-30 11:53:49 +01:00
scripts scripts: set proper OpenSSL include dir also for sign-file 2021-02-17 11:02:28 +01:00
security cap: fix conversions on getxattr 2021-02-17 11:02:22 +01:00
sound ASoC: Intel: sof_sdw: set proper flags for Dell TGL-H SKU 0A5E 2021-02-13 13:55:07 +01:00
tools selftests: txtimestamp: fix compilation issue 2021-02-17 11:02:26 +01:00
usr
virt KVM: Forbid the use of tagged userspace addresses for memslots 2021-02-03 23:28:41 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-12-10 15:30:13 -08:00
Makefile Linux 5.10.17 2021-02-17 11:02:30 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.