A firmware bug is present on the XPS Haswell edition which silently split the request in two responses when the caller ask for a read of more than 16 bytes. The FW sends the first 16 then the 4 next, but it says that it answered the 20 bytes in the first report.
This occurs only on the retrieving of the min/max of X and Y of the F11 function. We only use the first 10 bytes of the Ctrl register, so we can get only those 10 bytes to prevent the bug from happening. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1090161 Signed-off-by: Benjamin Tissoires <[email protected]> --- drivers/hid/hid-rmi.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c index 7da9509..cee89c9 100644 --- a/drivers/hid/hid-rmi.c +++ b/drivers/hid/hid-rmi.c @@ -613,10 +613,15 @@ static int rmi_populate_f11(struct hid_device *hdev) } } - /* retrieve the ctrl registers */ - ret = rmi_read_block(hdev, data->f11.control_base_addr, buf, 20); + /* + * retrieve the ctrl registers + * the ctrl register has a size of 20 but a fw bug split it into 16 + 4, + * and there is no way to know if the first 20 bytes are here or not. + * We use only the first 10 bytes, so get only them. + */ + ret = rmi_read_block(hdev, data->f11.control_base_addr, buf, 10); if (ret) { - hid_err(hdev, "can not read ctrl block of size 20: %d.\n", ret); + hid_err(hdev, "can not read ctrl block of size 10: %d.\n", ret); return ret; } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
