Re: [PATCH 0/9] platform/x86: lenovo-wmi-{other,capdata,helpers}: Improve robustness on buggy firmware

["Mark Pearson" <mpearson-lenovo@squebb.ca>]

On Wed, Oct 7, 2026, at 2:30 PM, Rong Zhang wrote:
> Hi Mark, Armin,
>
> 于 2026年9月29日 GMT+08:00 01:53:18，Rong Zhang <i@rong.moe> 写道：
>> Hi Mark, 
>> 
>> Thanks for the information. 
>> 
>> 于 2026年9月29日 GMT+08:00 00:04:14，Mark Pearson <mpearson-lenovo@squebb.ca> 写道：
>> > 
>> > 
>> > On Sat, Sep 26, 2026, at 11:01 PM, Rong Zhang wrote:
>> > > Hi Navon,
>> > >
>> > > Thanks a lot for your test. 
>> > >
>> > >
>> > > 于 2026年9月27日 GMT+08:00 05:04:15，Navon John Lukose 
>> > > <navonjohnlukose@gmail.com> 写道：
>> > >> Tested on a Yoga Pro 7 14IAH10 (83KF, BIOS QGCN35WW). Neither mainline
>> > >> nor the series binds here. This firmware has no
>> > >> LENOVO_CAPABILITY_DATA_01 in _WDG at all, so no component ever
>> > >> registers for that match and lwmi_om_master_bind() never runs. Skipping
>> > >> the match for GUIDs the firmware doesn't declare fixes it:
>> > >> 
>> > >> diff --git a/drivers/platform/x86/lenovo/wmi-capdata.c b/drivers/platform/x86/lenovo/wmi-capdata.c
>> > >> index 805e36ef7..d64520be1 100644
>> > >> --- a/drivers/platform/x86/lenovo/wmi-capdata.c
>> > >> +++ b/drivers/platform/x86/lenovo/wmi-capdata.c
>> > >> @@ -76,11 +76,13 @@ enum lwmi_cd_type {
>> > >>  #define LWMI_CD_TABLE_ITEM(_type)		\
>> > >>  	[_type] = {				\
>> > >>  		.name = #_type,			\
>> > >> +		.guid = _type##_GUID,		\
>> > >>  		.type = _type,			\
>> > >>  	}
>> > >>  
>> > >>  static const struct lwmi_cd_info {
>> > >>  	const char *name;
>> > >> +	const char *guid;
>> > >>  	enum lwmi_cd_type type;
>> > >>  } lwmi_cd_table[] = {
>> > >>  	LWMI_CD_TABLE_ITEM(LENOVO_CAPABILITY_DATA_00),
>> > >> @@ -166,6 +168,14 @@ void lwmi_cd_match_add_all(struct device *master, struct component_match **match
>> > >>  		if (lwmi_cd_table[i].type == LENOVO_FAN_TEST_DATA)
>> > >>  			continue;
>> > >>  
>> > >> +		/*
>> > >> +		 * Some firmware does not declare every capdata GUID at all, in
>> > >> +		 * which case no component would ever register for it and the
>> > >> +		 * master could never bind.
>> > >> +		 */
>> > >> +		if (!wmi_has_guid(lwmi_cd_table[i].guid))
>> > >> +			continue;
>> > >
>> > > This was exactly what I did in the earlier revision while I was 
>> > > introducing the support for capdata00 and capdata_fan.
>> > >
>> > > The wmi_has_guid() approach was eventually replaced by the 
>> > > sub-component approach, because the use of the former is strongly 
>> > > discouraged.
>> > >
>> > > In the next revision I am going to convert capdata01 into a 
>> > > sub-component, too. In this manner some heavy and complex work in the 
>> > > series will become needless and can be simplified. While the 
>> > > sub-component approach itself is complex, we've had the infrastructure 
>> > > to make it work. Therefore wiring it up should be a trivial work.
>> > >
>> > > Mark, Derek,
>> > >
>> > > Do you know if there is any way to determine the existence of capdata01 
>> > > using capdata00? 
>> > >
>> > Note that I can see I'm afraid
>
> So there is no way to determine the existence of capdata01 using 
> capdata00, correct?
>
>> > 
>> > I'm guessing the patch Armin posted on my thread "[RFC PATCH 5/7] platform/x86: think-lmi: Initial ThinkLMI v2 driver" to check if it exists won't help here?
>> 
>> After some consideration, it seems that we don't really need to determine the existence of capdata01 if we take the sub-component approach, thanks to the fact that every functionality either depends on capdata00 or depends on capdata01, but never both.
>
> Unfortunately, it turned out that it can't resolve the issue by simply 
> converting capdata01 into a sub-component, unless a virtual device is 
> also created to split the component matching list into two, which is 
> more like a dirty workaround.
>
> So yeah, the series needs the wmidev_exists() patch from Armin. 
> Considering that the ThinkLMI v2 series is probably still at the RFC 
> stage, do you mind if I integrate the wmidev_exists() patch into my 
> series?
>

Making good progress on that series but it's going to be a bit before it's ready for v1 submit as it's a significant rewrite.

No issues with wmidev_exists going in beforehand, but suggest we do it as a standalone all by itself patch so it doesn't get tied in to either of our review chains. Armin - does it make sense for you to push it? I'll happily add a tested-by tag.

Rong - As a note, I made a change to use a GUID string as input (I'll paste below to save you having to hunt for the email thread). If Armin is OK with it, I'd rather use this version.

Mark

bool wmidev_exists(const char *guid_string)
{
        guid_t guid;
        int ret;

        ret = guid_parse(guid_string, &guid);
        if (ret < 0)
                return false;

        return bus_for_each_dev(&wmi_bus_type, NULL, (void *)&guid, wmidev_match_guid) == 1;
}