Message-ID: <20250918164330.GN2912318@black.igk.intel.com>
Date: Thu, 18 Sep 2025 18:43:30 +0200
From: Mika Westerberg <mika.westerberg@...ux.intel.com>
To: 李佳怡 <lijiayi@...inos.cn>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	jiayi_dec@....com
Subject: Re: [PATCH RFC] thunderbolt: Re-add DP resources on resume

On Thu, Sep 18, 2025 at 06:20:59PM +0200, Mika Westerberg wrote:
> Hi,
> 
> On Thu, Sep 18, 2025 at 04:34:31PM +0800, 李佳怡 wrote:
> > 
> > 
> > 在 2025/9/17 20:50, Mika Westerberg 写道:
> > > On Wed, Sep 17, 2025 at 06:12:31PM +0800, 李佳怡 wrote:
> > > > 
> > > > As requested, I've attached the complete dmesg output (from boot to after
> > > > resume) reproducing the issue.
> > > > 
> > > > Testing Methodology:
> > > > 1. Start with the Targus Thunderbolt dock already connected to the system
> > > > 2. Enter S3 suspend (sleep) with no DP monitor connected to the dock
> > > > 3. Resume from S3
> > > > 4. After the system has fully resumed, connect the DP monitor to the dock
> > > 
> > > Thanks! It is badly line wrapped. I wonder if you can just attach it?
> > > Anyways I found some unexpected things there:
> > > 
> > > > [    8.647850] With USB4 patch v1.0.0
> > > 
> > > What is this? ;-)
> > 
> > Thanks for your help!
> > 
> > This is a self-compiled kernel based on version 5.4 with backported
> > Thunderbolt drivers. I will also attach the kernel log from a build using
> > the linux-6.6.y branch of the community linux-stable repository.
> 
> Okay but I really suggest using more recent kernel. 6.16 is current stable
> so that would be good.
> 
> > > > [    8.647860] ACPI: bus type thunderbolt registered
> > > > [    8.664660] [7] nhi_probe:1326: thunderbolt 0000:2c:00.0: total paths: 21
> > > > [    8.665209] [7] tb_ring_alloc:586: thunderbolt 0000:2c:00.0: allocating
> > > > TX ring 0 of size 10
> > > > [    8.665243] [7] tb_ring_alloc:586: thunderbolt 0000:2c:00.0: allocating
> > > > RX ring 0 of size 10
> > > > [    8.665267] [7] tb_ctl_alloc:665: thunderbolt 0000:2c:00.0: control
> > > > channel created
> > > > [    8.665272] [7] icm_probe:2549: thunderbolt 0000:2c:00.0: ICM not
> > > > supported on this controller
> > > > [    8.665285] [7] tb_ring_free:840: thunderbolt 0000:2c:00.0: freeing RX
> > > > ring 0
> > > > [    8.665294] [7] tb_ring_free:840: thunderbolt 0000:2c:00.0: freeing TX
> > > > ring 0
> > > 
> > > What is this?
> > > 
> > > Is this Intel TB/USB4 controller or something else? All USB4 compliant
> > > controllers should go directly to tb.c as that's the part dealing with
> > > software connection manager. The above looks like it tries first with the
> > > firmware connection manager and that should not happen outside of Intel
> > > Thunderbolt 3 hosts.
> > 
> > Yes, there is a mistake. I discovered that during the USB4_NATIVE_CONTROL
> > negotiation in the firmware, an OSC_CAPABILITIES_MASK_ERROR bit was being
> > set incorrectly, which should not have happened.
> > 
> > The log I will attach next has been modified to fix this issue.
> 
> [..]
> 
> > [    0.498976] [1] tb_switch_reset:1666: thunderbolt 0000:2c:00.0: 0: resetting
> > [    0.533329] [1] tb_add_dp_resources:217: thunderbolt 0000:2c:00.0: 0:10: DP IN resource available
> > [    0.533959] [1] tb_add_dp_resources:217: thunderbolt 0000:2c:00.0: 0:11: DP IN resource available
> 
> The DP IN resources were added here.
> 
> [..]
> 
> > [   19.035726] [171] tb_switch_set_wake:3445: thunderbolt 0000:2c:00.0: 0: enabling wakeup: 0x3f
> > [   19.037401] [171] tb_ring_stop:768: thunderbolt 0000:2c:00.0: stopping RX ring 0
> > [   19.037412] [171] ring_interrupt_active:141: thunderbolt 0000:2c:00.0: disabling interrupt at register 0x38200 bit 21 (0x200001 -> 0x1)
> > [   19.037439] [171] tb_ring_stop:768: thunderbolt 0000:2c:00.0: stopping TX ring 0
> > [   19.037449] [171] ring_interrupt_active:141: thunderbolt 0000:2c:00.0: disabling interrupt at register 0x38200 bit 0 (0x1 -> 0x0)
> > [   19.037463] [171] tb_ctl_stop:733: thunderbolt 0000:2c:00.0: control channel stopped
> 
> Runtime suspend.
> 
> (and a couple more)
> 
> > [  266.399800] [3870] tb_ctl_start:703: thunderbolt 0000:2c:00.0: control channel starting...
> > [  266.399808] [3870] tb_ring_start:693: thunderbolt 0000:2c:00.0: starting TX ring 0
> > [  266.399821] [3870] ring_interrupt_active:141: thunderbolt 0000:2c:00.0: enabling interrupt at register 0x38200 bit 0 (0x0 -> 0x1)
> > [  266.399826] [3870] tb_ring_start:693: thunderbolt 0000:2c:00.0: starting RX ring 0
> > [  266.399837] [3870] ring_interrupt_active:141: thunderbolt 0000:2c:00.0: enabling interrupt at register 0x38200 bit 21 (0x1 -> 0x200001)
> > [  266.399848] [3870] tb_switch_resume:3478: thunderbolt 0000:2c:00.0: 0: resuming switch
> > [  266.399852] [3870] tb_switch_configure:2590: thunderbolt 0000:2c:00.0: restoring Switch at 0x0 (depth: 0, up port: 5)
> > [  266.400032] [3870] tb_switch_set_wake:3447: thunderbolt 0000:2c:00.0: 0: disabling wakeup
> 
> Around this time you should see the hotplug events coming to the DP IN
> adapters. But there is none.
> 
> There is a bit in the DP adapter config space (DHP) that can be used to
> disable this but the spec says it defaults to 0. Anyways I suggest to check
> that (and also the Plugged bit). You can dump these using tbtools [1]. Let
> me know if you want help with that.

Nevermind about the Plugged bit, that's not applicable here.

Here's how to dump the DHP bit. This is from Intel host:

# tbdump -vv -r 0 -N 1 -a 5 ADP_CS_5
0x0005 0x00004809 0b00000000 00000000 01001000 00001001 ..H. ADP_CS_5
  [00:06]        0x9 Max Input HopID
  [11:17]        0x9 Max Output HopID
  [22:28]        0x0 Link Credits Allocated
  [29:29]        0x0 HEC Error Enable (HEE)
  [30:30]        0x0 Flow Control Error Enable (FCEE)
  [31:31]        0x0 Disable Hot Plug Events (DHP)

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