[PATCH v2 0/3] Bluetooth: btmtk: fix ISO data reception

[Chris Lu <chris.lu@mediatek.com>]

Three fixes for ISO data handling in btmtk, found while debugging LE Audio
on MT7925. The code is shared by every MediaTek USB controller that
supports ISO data, so none of this is specific to that part.

Patch 1 drops the zero padding that the ISO interrupt IN endpoint appends
to each transfer instead of parsing it as ISO packets. The driver turns
that padding into handle 0 packets with a Data_Total_Length of zero and
hands them to the stack, which is what fills the HCI log with malformed
ISO frames, and a valid SDU is lost whenever handle 0 belongs to a live
CIS/BIS.

Patch 2 bounds Data_Total_Length by hdev->iso_mtu. The existing
skb_tailroom() test enforces no protocol limit, because the skb head
allocation is rounded up to a kmalloc bucket and skb_tailroom() reports
the bucket size rather than what was requested.

Patch 3 updates the mt79xx ISO data transmission setting.

The three hunks do not overlap, so any prefix of the series applies on its
own.

Changes in v2:
- Patch 2 reworked and retitled. v1 only enlarged the receive skb, which
  turned out to be a no-op, and added no bound at all. v2 bounds
  Data_Total_Length by hdev->iso_mtu and sizes the skb from the same
  value.
- Patch 3 added.
- Patch 1 unchanged.

Based on bluetooth-next.

Chris Lu (3):
  Bluetooth: btmtk: drop zero-length ISO packets from endpoint padding
  Bluetooth: btmtk: bound the ISO payload length by the controller's MTU
  Bluetooth: btmtk: derive the firmware ISO setting from
    MTK_ISO_THRESHOLD

 drivers/bluetooth/btmtk.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

-- 
2.45.2