Hi Matthias,
> On WCN3990 downloading the NVM sometimes fails with a "TLV response
> size mismatch" error:
>
> [ 174.949955] Bluetooth: btqca.c:qca_download_firmware() hci0: QCA Downloading qca/crnv21.bin
> [ 174.958718] Bluetooth: btqca.c:qca_tlv_send_segment() hci0: QCA TLV response size mismatch
>
> It seems the controller needs a short time after downloading the
> firmware before it is ready for the NVM. A delay as short as 1 ms
> seems sufficient, make it 10 ms just in case. No event is received
> during the delay, hence we don't just silently drop an extra event.
>
> Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> ---
> I'm only guessing why the delay is needed, maybe QCA folks can shed
> more light on this.
>
> I didn't see this error when testing 2faa3f15fa2f ("Bluetooth: hci_qca:
> wcn3990: Drop baudrate change vendor event") and 32646db8cc28
> ("Bluetooth: btqca: inject command complete event during fw download")
> intensively a few months ago. My guess is that some changes in the kernel
> (I test with a 4.19 kernel with regular -stable merges) altered the
> timing, which made this issue visible.
> ---
> drivers/bluetooth/btqca.c | 3 +++
> 1 file changed, 3 insertions(+)
patch has been applied to bluetooth-next tree.
Regards
Marcel
