Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 11/10/2015 05:39 PM, Dave Young wrote:
Hi,

On 11/09/15 at 03:38pm, Lu Baolu wrote:
This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

I did a test with your previous patchset with the manually wired cable.
debug host detected the remote device, but later the devie automaticlly
disconnected and earlyprintk hangs.

Hi Dave,

What I have done is:

(1) Build a new kernel for debug target with this patch series applied.
(2) Add "earlyprintk=xdbc" to the kernel option of debug target. The
     "keep" option for early printk doesn't support yet. (That's my next
     target.)

(3) Boot the debug host, and disable USB runtime suspend:

# echo on > /sys/bus/pci/devices/<xhci_pci_bus_name>/power/control
# echo on | tee /sys/bus/usb/devices/*/power/control

(4) Boot the debug target. Check the dmesg message on debug host.

# tail -f /var/log/kern.log

Nov 12 01:27:50 allen-ult kernel: [ 1815.983374] usb 4-3: new SuperSpeed USB device number 4 using xhci_hcd Nov 12 01:27:50 allen-ult kernel: [ 1815.999595] usb 4-3: LPM exit latency is zeroed, disabling LPM. Nov 12 01:27:50 allen-ult kernel: [ 1815.999899] usb 4-3: New USB device found, idVendor=1d6b, idProduct=0004 Nov 12 01:27:50 allen-ult kernel: [ 1815.999902] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 Nov 12 01:27:50 allen-ult kernel: [ 1815.999903] usb 4-3: Product: Remote GDB Nov 12 01:27:50 allen-ult kernel: [ 1815.999904] usb 4-3: Manufacturer: Linux
Nov 12 01:27:50 allen-ult kernel: [ 1815.999905] usb 4-3: SerialNumber: 0001
Nov 12 01:27:50 allen-ult kernel: [ 1816.000240] usb_debug 4-3:1.0: xhci_dbc converter detected Nov 12 01:27:50 allen-ult kernel: [ 1816.000360] usb 4-3: xhci_dbc converter now attached to ttyUSB0

(5) Host has completed enumeration of debug device. Start "minicom" on debug host.


Welcome to minicom 2.7

OPTIONS: I18n
Compiled on Jan  1 2014, 17:13:19.
Port /dev/ttyUSB0, 01:28:02

Press CTRL-A Z for help on special keys

Press Y to continue...

(6) You should be able to see "Press Y to continue..." (if not, try pressing Enter key) Press Y key, debug target should go ahead with boot and early boot messages should show in mincom.

Press Y to continue...
[    0.000000] Initializing cgroup subsys cpuset
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Initializing cgroup subsys cpuacct
[ 0.000000] Linux version 4.3.0-rc7+ (allen@blu-skl) (gcc version 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04) 5 [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.3.0-rc7+ root=UUID=5a2fb856-0238-4b6e-aa45-beeccb7
[    0.000000] KERNEL supported cpus:

[...skipped...]

[    0.000000]  Offload RCU callbacks from CPUs: 0-7.
[    0.000000] Console: colour dummy device 80x25
[    0.000000] console [tty0] enabled
[    0.000000] bootconsole [earlyxdbc0] disabled


So "the devie automaticlly disconnected and earlyprintk hangs" happens in which step?

Thanks,
Baolu


I have not got more time, will try your new patchset when I have time.

Thanks
Dave


--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux