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
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