On Sunday, July 11, 2021 8:33:57 AM PDT Pauli Virtanen wrote: > pe, 2021-05-14 kello 11:19 +0800, hildawu@xxxxxxxxxxx kirjoitti: > > Because mSBC frames do not need to be aligned to the SCO packet > > boundary. Using USB ALT 3 let HCI payload >= 60 bytes, let mSBC > > data satisfy 60 Bytes avoid payload unaligned situation and fixed > > some headset no voise issue. > > > > USB Alt 3 supported also need HFP support transparent MTU in 72 > > Bytes. > > This change seemed to break msbc audio on some non-realtek adapters I > have. Tested Pipewire on BCM20702A1 (0b05:17cb), CSR8510A10 (0a12:0001) > -> no sound output and input appears garbled. Reverting this patch > makes it work again. Indeed these adapters report SCO mtu=64 which is > less than 72. On the other hand, with RTL8761BU (0bda:8771) msbc audio > works fine with this patch out of the box, indeed reading/writing 72 > byte packets to/from the sco socket When I fixed WBS when previous patches from Intel and Realtek broke it for most adapters, I also tested alt 3. I also found it didn't work for many adapters. It is annoying that a chipset vendor can not be bothered to do the basic testing I am able to do by buying random bt adapters from amazon. Nor respond when their patches, once accepted, cause problems.
