[PW_SID:1100446] [v3] Bluetooth: Add Broadcom channel priority commands#237
[PW_SID:1100446] [v3] Bluetooth: Add Broadcom channel priority commands#237BluezTestBot wants to merge 1 commit into
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Certain Broadcom bluetooth chips (bcm4377/bcm4378/bcm438) need ACL streams carrying audio to be set as "high priority" using a vendor specific command to prevent 10-ish second-long dropouts whenever something does a device scan. This patch sends the command when the socket priority is set to TC_PRIO_INTERACTIVE, as BlueZ does for audio. From experimenting with the hardware - this command is not suitable for per-skb priority switching, as prioritization is done on the handle level, with this command reconfiguring certain radio timings, and dropping to low priority in order to send a low packet on the same handle as an audio stream is being played on causes the same kind of dropout it is supposed to avoid. In addition, the hardware is rather picky about when this command can be sent, as sending it during connection open results in a timeout. The vendor stacks solve it by having high-level visibility into what a connection is used for and sending it from userspace when it is known that an audio stream is about to start. As we can't have that visibility without introducing a new ioctl, the socket priority is used as proxy. Reviewed-by: Neal Gompa <neal@gompa.dev> Signed-off-by: Sasha Finkelstein <k@chaosmail.tech>
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2 participants
Certain Broadcom bluetooth chips (bcm4377/bcm4378/bcm438) need ACL
streams carrying audio to be set as "high priority" using a vendor
specific command to prevent 10-ish second-long dropouts whenever
something does a device scan. This patch sends the command when the
socket priority is set to TC_PRIO_INTERACTIVE, as BlueZ does for audio.
From experimenting with the hardware - this command is not suitable for
per-skb priority switching, as prioritization is done on the handle
level, with this command reconfiguring certain radio timings, and
dropping to low priority in order to send a low packet on the same
handle as an audio stream is being played on causes the same kind of
dropout it is supposed to avoid. In addition, the hardware is rather
picky about when this command can be sent, as sending it during
connection open results in a timeout. The vendor stacks solve it by
having high-level visibility into what a connection is used for and
sending it from userspace when it is known that an audio stream is
about to start. As we can't have that visibility without introducing a
new ioctl, the socket priority is used as proxy.
Reviewed-by: Neal Gompa neal@gompa.dev
Signed-off-by: Sasha Finkelstein k@chaosmail.tech
Changes in v3:
Changes in v2:
MAINTAINERS | 2 ++
drivers/bluetooth/hci_bcm4377.c | 2 ++
include/net/bluetooth/hci_core.h | 15 +++++++++++++++
net/bluetooth/Kconfig | 7 +++++++
net/bluetooth/Makefile | 1 +
net/bluetooth/brcm.c | 38 ++++++++++++++++++++++++++++++++++++++
net/bluetooth/brcm.h | 19 +++++++++++++++++++
net/bluetooth/hci_core.c | 4 ++++
8 files changed, 88 insertions(+)
base-commit: 8bc67e4db64aa72732c474b44ea8622062c903f0
change-id: 20260407-brcm-prio-b630e6cc3834
Best regards,
Sasha Finkelstein k@chaosmail.tech