Return-Path: MIME-Version: 1.0 From: Mirza Krak Date: Thu, 1 Feb 2018 10:58:28 +0100 Message-ID: Subject: High CPU load when using USB Bluetooth on 4.14.15-rt13 kernel To: linux-bluetooth@vger.kernel.org Cc: marcel@holtmann.org, linux-rt-users@vger.kernel.org Content-Type: text/plain; charset="UTF-8" List-ID: Hi. As I mentioned in the subject I am running a 4.14.15-rt13 kernel. The hardware is a RK3288 SoC and this combination is producing a heavy CPU load when an USB Bluetooth controller is simply powered on without the need of connecting to any device. I am running bluez5 (5.46). This is what it looks like: 92 2 root RW 0 0% 20% [irq/45-dwc2_hso] 91 2 root RW 0 0% 11% [irq/45-ff540000] Above is the USB interrupts of the controller where the USB bluetooth device is connected and it is simply power on without doing anything. Turning the controller off: [bluetooth]# power off Changing power off succeeded [CHG] Controller 00:15:83:EA:73:23 Powered: no [CHG] Controller 00:15:83:EA:73:23 Discovering: no [CHG] Controller 00:15:83:EA:73:23 Class: 0x000000 And the CPU load is down to minimal: 92 2 root SW 0 0% 2% [irq/45-dwc2_hso] 91 2 root SW 0 0% 2% [irq/45-ff540000] I have tried two different USB Bluetooth devices: Bus 001 Device 003: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode) Bus 001 Device 005: ID 0a5c:4500 Broadcom Corp. BCM2046B1 USB 2.0 Hub (part of BCM2046 Bluetooth) With the same result. I have also tried running a WLAN USB device and this does not produce any high CPU load. So fairly isolated to USB Bluetooth. I have tried running a 4.14.15 vanilla kernel, and this does not have this problem which means that it is the following combo RT + USB Bluetooth That seem to the problem. Before I start digging deep in to the stacks I wanted to post my problem to the community to see if someone is having a similar problem on a different hardware or if you have any pointers on how to further debug this. --=20 Med V=C3=A4nliga H=C3=A4lsningar / Best Regards Mirza Krak