Hi Oliver, >-----Original Message----- >From: Oliver Neukum <oneukum@xxxxxxxx> >Sent: Thursday, May 16, 2024 11:28 AM >To: K, Kiran <kiran.k@xxxxxxxxx>; Marcel Holtmann <marcel@xxxxxxxxxxxx> >Cc: linux-bluetooth@xxxxxxxxxxxxxxx >Subject: question regarding ordering in btintel_pcie_send_sync() > >Hi, > >I was looking at the code. I do not have documentation for the device, but it >looks relatively ordinary. Hence this piece of code caught my eye: > > > /* Set the doorbell to notify the device */ > btintel_pcie_set_tx_db(data, tfd_index); > >Requesting an interrupt. However, are you sure the IO can be processed and >trigger an interrupt only after the PCI write, which this triggers? > This wait is for reception of packet at the device side. Bluetooth controller can raise the interrupt with different causes. Here driver waits for interrupt BTINTEL_*_CAUSE_0 which indicates that TX has been completed. Device raises BTINTEL_*_CAUSE_1 interrupt when TX packet has been processed and there is some data in RX queue to be read by driver. > /* Wait for the complete interrupt - URBD0 */ > ret = wait_event_timeout(data->tx_wait_q, data->tx_wait_done, > msecs_to_jiffies(BTINTEL_PCIE_TX_WAIT_TIMEOUT_MS)); > > Regards > Oliver Thanks, Kiran
