On Tue, Apr 02, 2019 at 05:32:54PM +0530, Balakrishna Godavarthi wrote: > Hi Matthias, > > On 2019-04-01 22:42, Matthias Kaehlcke wrote: > > On Mon, Apr 01, 2019 at 01:48:23PM +0530, Balakrishna Godavarthi wrote: > > > Hi Matthias, > > > > > > On 2019-04-01 13:29, Balakrishna Godavarthi wrote: > > > > Hi Matthias, > > > > > > > > Sorry for the late reply i was on vacation. > > > > > > > > On 2019-03-08 05:00, Matthias Kaehlcke wrote: > > > > > On Thu, Mar 07, 2019 at 10:20:09AM -0800, Matthias Kaehlcke wrote: > > > > > > Hi Balakrishna, > > > > > > > > > > > > On Thu, Mar 07, 2019 at 10:35:08AM +0530, Balakrishna Godavarthi > > > > > > wrote: > > > > > > > hi Matthias, > > > > > > > > > > > > > > On 2019-03-07 06:10, Matthias Kaehlcke wrote: > > > > > > > > Firmware download to the WCN3990 often fails with a 'TLV response size > > > > > > > > mismatch' error: > > > > > > > > > > > > > > > > [ 133.064659] Bluetooth: hci0: setting up wcn3990 > > > > > > > > [ 133.489150] Bluetooth: hci0: QCA controller version 0x02140201 > > > > > > > > [ 133.495245] Bluetooth: hci0: QCA Downloading qca/crbtfw21.tlv > > > > > > > > [ 133.507214] Bluetooth: hci0: QCA TLV response size mismatch > > > > > > > > [ 133.513265] Bluetooth: hci0: QCA Failed to download patch (-84) > > > > > > > > > > > > > > > > This is caused by a vendor event that corresponds to an earlier command > > > > > > > > to change the baudrate. The event is not processed in the context of the > > > > > > > > baudrate change and later interpreted as response to the firmware > > > > > > > > download command (which is also a vendor command), but the driver > > > > > > > > detects > > > > > > > > that the event doesn't have the expected amount of associated data. > > > > > > > > > > > > > > > > More details: > > > > > > > > > > > > > > > > For the WCN3990 the vendor command for a baudrate change isn't sent as > > > > > > > > synchronous HCI command, because the controller sends the corresponding > > > > > > > > vendor event with the new baudrate. The event is received and decoded > > > > > > > > after the baudrate change of the host port. > > > > > > > > > > > > > > > > Identify the 'unused' event when it is received and don't add it to > > > > > > > > the queue of RX frames. > > > > > > > > > > > > > > > > Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> > > > > > > > > --- > > > > > > > > > > > > > > ... > > > > > > > > > > > > > > Can you test by reverting this change "94d6671473924". > > > > > > > > > > > > The issue is still reproducible. > > > > > > > > > > > > > We need at least 15ms minimum delay for the soc to change its baud rate and > > > > > > > respond to the with command complete event. > > > > > > > > > > > > The baudrate change has clearly been successful when the problem is > > > > > > observed, since the host receives the vendor event with the new > > > > > > baudrate. > > > > > > > > > > I forgot to mention this earlier: the controller doesn't send a > > > > > command complete event for the command, or at least not a correct > > > > > one. > > > > > > > > > > That's the data that is received: > > > > > > > > > > 04 0e 04 01 00 00 00 > > > > > ~~ ~~ > > > > > > > > > [Bala]: can you share me the command sent and event recevied. > > > > I see that we receive a command complete event for the baud rate > > > > change command. > > > > > > > > command sent: 01 48 fc 01 11 > > > > vendor specific event: 04 ff 02 92 01 > > > > command complete event: 04 0e 04 01 00 00 00. > > > > > > > > > > > > > > > > > This is *a* command complete event, but the opcode is 0x0000 instead > > > > > of the earlier command. The same happens for the firmware > > > > > download/read version command, which is the reason why the command > > > > > complete injection mess > > > > > (https://lore.kernel.org/patchwork/patch/1027955/) is needed in one > > > > > way or another. > > > > > > > > > [Bala]: fw download approach is different where we use > > > > __hci_cmd_sync() where as here we use hci_uart_tx_wakeup() > > > > which directly calls the hci_uart_write_work(). so even we > > > > send an valid opcode or not for baudrate change will bot matter. > > > > > > > [Bala]: i miss understood the comment. Yes your true. in the all > > > vendor > > > commands SoC responds with an 0x0000 opcode. > > > > And IIUC this is not compliant with the spec, or at least the BT core > > expects the actual opcode to consider the command to be completed. > > [Bala]: Did you try increasing the the baud rate change timeout to 50ms > instead of 10ms. It is even reproducible with the ROME timeout of 300ms. The timeout doesn't help here. With 78e8fa2972e5 ("Bluetooth: hci_qca: Deassert RTS while baudrate change command") RTS is deasserted during the baudrate change, hence the controller only sends the response when RTS is asserted again. Before the event resulted in a frame reassembly error and the data was discarded. > i suspect it is an timing issue. Timing is certainly also a factor here (the problem isn't seen always), but I don't think 'timing issue' is a proper description of this issue. The problem is an event that the Bluetooth core doesn't expect due to the hack of sending a raw command behind the core's back to work around the firmware 'feature' of sending the command response with the new baudrate. Maybe a delay after re-asserting RTS can address is reliably, I don't remember if I already experimented with that in the past. If a delay can 'fix' the issue reliably I'm open to consider it for the sake of simplicity, but only with a detailed comment that describes the problem.
