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authorHui Wang <hui.wang@canonical.com>2020-12-11 10:18:14 +0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-12-15 19:30:49 +0100
commitb08221c40febcbda9309dd70c61cf1b0ebb0e351 (patch)
tree3802721992cfd11ed597d208b422768af01d7f54 /drivers/acpi
parent0477e92881850d44910a7e94fc2c46f96faa131f (diff)
downloadlinux-b08221c40febcbda9309dd70c61cf1b0ebb0e351.tar.bz2
ACPI: PNP: compare the string length in the matching_id()
Recently we met a touchscreen problem on some Thinkpad machines, the touchscreen driver (i2c-hid) is not loaded and the touchscreen can't work. An i2c ACPI device with the name WACF2200 is defined in the BIOS, with the current rule in matching_id(), this device will be regarded as a PNP device since there is WACFXXX in the acpi_pnp_device_ids[] and this PNP device is attached to the acpi device as the 1st physical_node, this will make the i2c bus match fail when i2c bus calls acpi_companion_match() to match the acpi_id_table in the i2c-hid driver. WACF2200 is an i2c device instead of a PNP device, after adding the string length comparing, the matching_id() will return false when matching WACF2200 and WACFXXX, and it is reasonable to compare the string length when matching two IDs. Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Hui Wang <hui.wang@canonical.com> Cc: All applicable <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/acpi_pnp.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/acpi/acpi_pnp.c b/drivers/acpi/acpi_pnp.c
index 4ed755a963aa..8f2dc176bb41 100644
--- a/drivers/acpi/acpi_pnp.c
+++ b/drivers/acpi/acpi_pnp.c
@@ -319,6 +319,9 @@ static bool matching_id(const char *idstr, const char *list_id)
{
int i;
+ if (strlen(idstr) != strlen(list_id))
+ return false;
+
if (memcmp(idstr, list_id, 3))
return false;