Re: [PATCH] platform/x86: intel-vbtn: Support for tablet mode on Dell Venue 11 Pro 7140

[Hans de Goede]

Hi Kostadin,

On 7/25/24 8:26 PM, Kostadin Stoilov wrote:
> Hi Hans,
> 
> I tested a kernel built by En-Wei with your patch and I can confirm that it resolves the issue. I tried several connect/disconnect suspend/resume cycles.
> 
> The kernel bug messages are not observed and the system suspend/resumes/powers off successfully.
> 
> The dmesg log from the test run can be found here:
> https://launchpadlibrarian.net/740661223/6.10-maintainer-dmesg.txt <https://launchpadlibrarian.net/740661223/6.10-maintainer-dmesg.txt>

Thank you for testing. I've now done an official submission of this patch upstream:

https://lore.kernel.org/platform-driver-x86/20240729110030.8016-1-hdegoede@xxxxxxxxxx/

This should be included in a fixes pull-req for 6.11 soon-ish and then get backported to various
stable kernel series.

Regards.

Hans


> On Mon, 22 Jul 2024 at 12:45, Hans de Goede <hdegoede@xxxxxxxxxx <mailto:hdegoede@xxxxxxxxxx>> wrote:
> 
>     Hi En-Wei,
> 
>     On 7/22/24 10:36 AM, En-Wei Wu wrote:
>     > On a Dell Venue 7140 tablet with the keyboard/touchpad/battery dock, when
>     > disconnecting the dock there is a kernel bug:
>     >
>     > BUG: kernel NULL pointer dereference, address: 0000000000000018
>     >
>     > And this causes the following things not to work:
>     > 1. Suspend to idle - the system simply hangs
>     > 2. Poweroff normally (the only way is forcing it via long press the power button)
>     > 3. USB ports: both the USB port on the tablet and also plugging in the keyboard again
>     >
>     > The error message above (plus some crash dump) isn't so useful for debugging, but we
>     > have noticed that there is a debug message shown before the crash dump:
>     >
>     > intel-vbtn INT33D6:00: Registering Intel Virtual Switches input-dev after receiving
>     > a switch event
>     >
>     > The messages above is shown right after the dock is disconnected, and the message implies:
>     >
>     > We failed to set the priv->has_switches to true in the probe function since the
>     > Dell Venue 11 Pro 7140 is not shown in the dmi_switches_allow_list, and this causes a problem
>     > that no input_register_device() on the switch device is called. Afterward, When a user
>     > disconnects the dock, intel-vbtn receives the ACPI event and finally find that there is a
>     > switch out there. So intel-vbtn starts to register the switch device, which may be a dangerous
>     > behavior since there might be some device-related objects/structs that has been freed (due to
>     > the disconnection of the dock).
>     >
>     > To solve this problem from the root cause, simply add the Dell Venue 11 pro 7140 to the
>     > dmi_switches_allow_list.
>     > (The Dell Venue 11 Pro 7140 is a 2-in-1 model that has chassis-type "Portable".)
>     >
>     > BugLink: https://bugs.launchpad.net/bugs/2073001 <https://bugs.launchpad.net/bugs/2073001>
>     >
>     > Fixes: 8169bd3e6e19 ("platform/x86: intel-vbtn: Switch to an allow-list
>     > for SW_TABLET_MODE reporting")
>     > Reported-by: Kostadin Stoilov <kmstoilov@xxxxxxxxx <mailto:kmstoilov@xxxxxxxxx>>
>     > Tested-by: Kostadin Stoilov <kmstoilov@xxxxxxxxx <mailto:kmstoilov@xxxxxxxxx>>
>     > Signed-off-by: En-Wei Wu <en-wei.wu@xxxxxxxxxxxxx <mailto:en-wei.wu@xxxxxxxxxxxxx>>
> 
>     Thank you for your patch. Looking at the logs from the launchpad bug I noticed that
> 
>     intel-vbtn INT33D6:00: Registering Intel Virtual Switches input-dev after receiving a switch event
> 
>     is reported in the logs twice. Which strongly suggests that the intel-vbtn notify_handler()
>     function is racing with itself.
> 
>     In the past ACPI notify handlers could never run more then once (at the same time)
>     but since commit e2ffcda16290 ("ACPI: OSL: Allow Notify () handlers to run on
>     all CPUs") ACPI notify handlers like the intel-vbtn notify_handler() may
>     run on multiple CPU cores racing with themselves.
> 
>     I believe that this is the real problem here. I have attached a patch which should
>     fix this. Can you build a test-kernel with this patch instead of your patch and
>     ask the reported of: https://bugs.launchpad.net/bugs/2073001 <https://bugs.launchpad.net/bugs/2073001>
> 
>     To test a kernel with the attached patch (and without your patch) to confirm
>     that this fixes it in a more generic manner ?
> 
>     Regards,
> 
>     Hans
> 
> 
> 
> 
> 
>     > ---
>     >  drivers/platform/x86/intel/vbtn.c | 6 ++++++
>     >  1 file changed, 6 insertions(+)
>     >
>     > diff --git a/drivers/platform/x86/intel/vbtn.c b/drivers/platform/x86/intel/vbtn.c
>     > index 9b7ce03ba085..46d07d3cd34b 100644
>     > --- a/drivers/platform/x86/intel/vbtn.c
>     > +++ b/drivers/platform/x86/intel/vbtn.c
>     > @@ -235,6 +235,12 @@ static const struct dmi_system_id dmi_switches_allow_list[] = {
>     >                       DMI_MATCH(DMI_PRODUCT_NAME, "Venue 11 Pro 7130"),
>     >               },
>     >       },
>     > +     {
>     > +             .matches = {
>     > +                     DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
>     > +                     DMI_MATCH(DMI_PRODUCT_NAME, "Venue 11 Pro 7140"),
>     > +             },
>     > +     },
>     >       {
>     >               .matches = {
>     >                       DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
>