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

[Navon John Lukose]

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;
+
 		component_match_add(master, matchptr, lwmi_cd_match,
 				    (void *)&lwmi_cd_table[i].type);
 		if (IS_ERR(*matchptr))
diff --git a/drivers/platform/x86/lenovo/wmi-other.c b/drivers/platform/x86/lenovo/wmi-other.c
index e6c8f6bcf..b196e9926 100644
--- a/drivers/platform/x86/lenovo/wmi-other.c
+++ b/drivers/platform/x86/lenovo/wmi-other.c
@@ -1704,6 +1704,8 @@ static int lwmi_other_probe(struct wmi_device *wdev, const void *context)
 	lwmi_cd_match_add_all(&wdev->dev, &master_match);
 	if (IS_ERR(master_match))
 		return PTR_ERR(master_match);
+	if (!master_match)
+		return -ENODEV;
 
 	return component_master_add_with_match(&wdev->dev, &lwmi_om_master_ops,
 					       master_match);

With that on top (built out of tree against 7.2.5), lenovo_wmi_other
binds and exposes fan1 and fan4 (min 1500/1800, max 5100/5400, input
matching the EC tach fields). fanX_target pins both fans, 0 hands them
back to the firmware curve, and out-of-range writes get -EINVAL. With
the change above:

Tested-by: Navon John Lukose <navonjohnlukose@xxxxxxxxx>