Re: [PATCH v2 1/1] platform/x86: asus-wmi: disable USB0 hub on ROG Ally before suspend
From: Armin Wolf
Date: Mon Nov 27 2023 - 20:17:15 EST
Am 28.11.23 um 01:54 schrieb Luke Jones:
On Mon, Nov 27 2023 at 10:42:48 PM +01:00:00, Armin Wolf
<W_Armin@xxxxxx> wrote:
Am 27.11.23 um 21:55 schrieb Mario Limonciello:
On 11/27/2023 14:46, Luke Jones wrote:
On Mon, Nov 27 2023 at 02:14:23 PM -06:00:00, Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
On 11/26/2023 17:05, Luke D. Jones wrote:
ASUS have worked around an issue in XInput where it doesn't
support USB
selective suspend, which causes suspend issues in Windows. They
worked
around this by adjusting the MCU firmware to disable the USB0
hub when
the screen is switched off during the Microsoft DSM suspend path
in ACPI.
The issue we have with this however is one of timing - the call
the tells
the MCU to this isn't able to complete before suspend is done so
we call
this in a prepare() and add a small msleep() to ensure it is
done. This
must be done before the screen is switched off to prevent a
variety of
possible races.
Right now the way that Linux handles the LPS0 calls is that
they're all back to back. Luke did try to inject a delay after
the LPS0 calls were done but before it went to sleep but this
wasn't sufficient.
Another "potential" way to solve this problem from Linux may be
to actually glue the LPS0 screen off call to when DRM actually has
eDP turned off.
Making such a change would essentially push back the "screen off"
LPS0 command to when the user has run 'systemctl suspend' (or an
action that did this) because the compositor usually turns it off
with DPMS at this time.
I would be willing to test this if you want some concrete data.
It would require some cross subsystem plumbing to evaluate
feasibility.
I don't currently have any plans to do it.
I think your patch makes sense; I just want to make it known that
"might" clean this up if it ever happens.
See my big block of text below.
This is a much bigger change though and *much more ripe for
breakage*.
So I think in may be worth leaving a TODO comment to look into
doing that in the future.
Do you mean add the TODO to a line in this patch?
Yeah. In case someone ever does it (me or otherwise) I think it
would be good to have some reference in the comments that the commit
'might' be possible to revert.
If that ever happens; it's possible that this change could be
reverted too.
Further to this the MCU powersave option must also be disabled
as it can
cause a number of issues such as:
- unreliable resume connection of N-Key
- complete loss of N-Key if the power is plugged in while suspended
Disabling the powersave option prevents this.
Without this the MCU is unable to initialise itself correctly on
resume.
initialize
Are we forced to use USA spelling? I'm from NZ
"initialise is predominantly used in British English (used in
UK/AU/NZ) ( en-GB )"
Ah I didn't realize it's an acceptable spelling for en-GB, and
thought it was just a typo; sorry.
Signed-off-by: Luke D. Jones <luke@xxxxxxxxxx>
I think it would be good to add a Closes: tag to the AMD Gitlab
issue that this was discussed within as well as any other public
references you know about.
Additionally as Phoenix APU support goes back as far as kernel
6.1 and this is well contained to only run on the ROG I suggest to
CC stable so that people can use the ROG on that LTS kernel or later.
---
-SNIP-
@@ -4701,6 +4749,8 @@ static const struct dev_pm_ops
asus_pm_ops = {
.thaw = asus_hotk_thaw,
.restore = asus_hotk_restore,
.resume = asus_hotk_resume,
+ .resume_early = asus_hotk_resume_early,
+ .prepare = asus_hotk_prepare,
Have you experimented with only using the prepare() call or only
the resume_early() call? Are both really needed?
I have yes. Although the device comes back eventually in resume
after only a prepare call it's not preferable as it tends to change
the device path. With resume_early we can get the device replugged
super early (before anything notices it's gone in fact).
This whole thing is a bit of a mess. It ends up being a race
between various things to prevent a HUB0 disconnect being
registered by the xhci subsystem, and adding the device back before
the xhci subsystem gets control.
If I add a sleep longer than 1300ms in prepare then the xhci
subsys registers a disconnect of the USB0 hub. If the sleep is
under 250ms it isn't quite enough for the MCU to do its thing, and
on battery it seems worse.
I have asked the ASUS guys I'm in contact with for something to
disable this MCU behaviour since it is purely a workaround for a
broken Windows thing :( They are open to something, maybe an OS
detect in ACPI or a WMI method addition similar to the MCU
powersave method, from what I'm told it would require an MCU
firmware update along with BIOS update. If this eventuates I'll
submit an additional patch to check and set that plus disable this.
Don't let them do an OS detection in ACPI, it's going to be too
painful.
I would instead suggest that they can have a bit that you can
program in via ACPI or WMI from the ASUS WMI driver that says to
skip the MCU disconnect behavior.
I totally agree, we do not need another _OSI(Linux) type of problem.
Maybe those guys at Asus could just implement a ACPI _DSM for the USB
controller in question which allows for disabling this workaround.
This would be preferable to an additional WMI method, since the
notebook would otherwise depend on the asus-wmi driver to suspend
properly.
With the ACPI _DSM, the USB controller driver can disable the
workaround as soon as the USB controller probes.
Would you be so kind as to explain what this means? My knowledge of
ACPI is paper thin and generally revolves just around the ASUS WMI
part. From what i can find the XHC0 (the hub the MCU is attached to)
doesn't have any current _DSM. I understand it means Device Specific
Method, so I guess you mean adding a method to be used only if that
HUB is there and implements it?
The ROG Ally depends on the asus-wmi driver regardless, without it, it
is barely functional.
An ACPI _DSM method is a "standardized" way for manufacturers to add device specific methods to ACPI devices, see
https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/09_ACPI-Defined_Devices_and_Device-Specific_Objects/ACPIdefined_Devices_and_DeviceSpecificObjects.html for details.
Implementing via a ACPI _DSM would contain the necessary logic for USB suspend inside the USB hub driver, instead of forcing asus-wmi and the USB hub driver
to collaborate on USB suspend. The USB hub driver would discover this device specific method during probe and disable the workaround, leaving no chance for
race conditions between asus-wmi and the USB hub driver to develop.
Of course if the ROG Ally depends on asus-wmi regardless, then Asus could as well use the WMI interface for this. But IMHO standard ACPI interfaces should be
preferred to custom ones like WMI.
Armin Wolf
I may possibly write a new version of this patch as we've seen
that enabling powersave reduces suspend power use by at least half.
And looking through my DSDT dumps, there are a few laptops with the
same feature as Ally. The patch for powersave being enabled
requires also AC power state on suspend change detection, and a
later forced reset in late resume (and the device paths change
regardless when powersave is on).
When I look at it objectively, the device path changing should be
a non-issue really as it is fully handled by USB subsystem and
behaves exactly like what it is - a USB hub disconnect. It's just
that some userspace apps don't expect this. I will experiment some
more.
Regards,
Luke.
As another experiment - what happens if you "comment out" the LPS0
calls that do this problematic stuff?
It's important to make sure the callback to amd-pmc stays in place,
but if you just skip those ACPI ones does it still get to the
deepest state and are there other problems?
};
/* Registration
***************************************************************/
diff --git a/include/linux/platform_data/x86/asus-wmi.h
b/include/linux/platform_data/x86/asus-wmi.h
index 63e630276499..ab1c7deff118 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -114,6 +114,9 @@
/* Charging mode - 1=Barrel, 2=USB */
#define ASUS_WMI_DEVID_CHARGE_MODE 0x0012006C
+/* MCU powersave mode */
+#define ASUS_WMI_DEVID_MCU_POWERSAVE 0x001200E2
+
/* epu is connected? 1 == true */
#define ASUS_WMI_DEVID_EGPU_CONNECTED 0x00090018
/* egpu on/off */