From: Peter Zijlstra <peterz@infradead.org>
To: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
Dave Hansen <dave.hansen@intel.com>,
Lu Baolu <baolu.lu@linux.intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org,
Chunfeng Yun <chunfeng.yun@mediatek.com>
Subject: Re: earlyprintk=xdbc seems broken
Date: Fri, 17 Dec 2021 14:55:07 +0100 [thread overview]
Message-ID: <YbyWuxoBSicFBGuv@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <c2b5c9bb-1b75-bf56-3754-b5b18812d65e@linux.intel.com>
On Fri, Dec 17, 2021 at 01:01:43PM +0200, Mathias Nyman wrote:
> I can reproduce this.
> Looks like problems started when driver converted to readl_poll_timeout_atomic() in:
>
> 796eed4b2342 usb: early: convert to readl_poll_timeout_atomic()
I can confirm, reverting that solves the boot hang, things aren't quite
working for me though.
> Seems to hang when read_poll_timeout_atomic() calls ktime_* functions.
> Maybe it's too early for ktime.
It certainly is, using ktime for delay loops sounds daft to me anyhow.
> After reverting that patch it works again for me.
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-5.16.0-rc3+ root=UUID=a652986c-fbc6-4341-85c3-b4ad4402f130 ro debug ignore_loglevel sysrq_always_enabled usbcore.autosuspend=-1 earlyprintk=xdbc force_early_printk sched_verbose ftrace=nop mitigations=off nokaslr
...
[ 0.000000] xhci_dbc:early_xdbc_parse_parameter: dbgp_num: 0
...
[ 3.161367] xhci_dbc:early_xdbc_setup_hardware: failed to setup the connection to host
The machine does boot.. but I *am* getting tons of:
[ 485.546898] usb usb4-port4: Cannot enable. Maybe the USB cable is bad?
[ 485.546963] usb usb4-port4: config error
However, when I do:
$ echo enable > /sys/bus/pci/devices/0000:00:14.0/dbc
I get:
[ 569.442899] xhci_hcd 0000:00:14.0: DbC connected
[ 569.898910] xhci_hcd 0000:00:14.0: DbC configured
And the remote machine gets:
[2318863.729022] usb 2-3: new SuperSpeed USB device number 8 using xhci_hcd
[2318863.749299] usb 2-3: LPM exit latency is zeroed, disabling LPM.
[2318863.749529] usb 2-3: New USB device found, idVendor=1d6b, idProduct=0010, bcdDevice= 0.10
[2318863.749531] usb 2-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[2318863.749532] usb 2-3: Product: Linux USB Debug Target
[2318863.749533] usb 2-3: Manufacturer: Linux Foundation
[2318863.749534] usb 2-3: SerialNumber: 0001
[2318863.751142] usb_debug 2-3:1.0: xhci_dbc converter detected
[2318863.751268] usb 2-3: xhci_dbc converter now attached to ttyUSB0
and a subsequent:
$ echo ponies > /dev/ttyDBC0
Does show up on the remote machine...
So XDBC 'works' but earlyprintk is still refusing service.
next prev parent reply other threads:[~2021-12-17 13:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-02 15:22 earlyprintk=xdbc seems broken Peter Zijlstra
2021-12-03 0:52 ` Lu Baolu
2021-12-03 14:31 ` Mathias Nyman
2021-12-03 15:22 ` Dave Hansen
2021-12-03 15:29 ` Greg KH
2021-12-17 11:01 ` Mathias Nyman
2021-12-17 13:55 ` Peter Zijlstra [this message]
2021-12-17 15:19 ` Greg KH
2021-12-20 14:40 ` Peter Zijlstra
2021-12-20 15:06 ` Greg KH
2021-12-20 17:01 ` Peter Zijlstra
2021-12-20 14:34 ` Mathias Nyman
2021-12-20 15:51 ` Peter Zijlstra
2021-12-21 9:40 ` Peter Zijlstra
2021-12-21 9:41 ` Peter Zijlstra
2022-01-14 8:47 ` Peter Zijlstra
2022-01-14 19:31 ` Mathias Nyman
2022-01-15 16:06 ` Peter Zijlstra
2022-01-24 14:55 ` Mathias Nyman
2022-01-24 16:39 ` Peter Zijlstra
2022-01-24 16:46 ` Peter Zijlstra
2022-01-25 8:51 ` Mathias Nyman
2022-01-25 10:47 ` Peter Zijlstra
2022-01-25 10:54 ` Peter Zijlstra
2022-01-25 12:45 ` Peter Zijlstra
2022-01-25 13:09 ` Sven Schnelle
2022-01-25 13:54 ` Peter Zijlstra
2022-01-25 14:01 ` Sven Schnelle
2022-01-25 17:13 ` Mathias Nyman
2022-01-25 16:24 ` Dave Hansen
2022-02-17 3:44 ` Randy Dunlap
2022-01-25 19:39 ` Rajaram R
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