[PATCH] Input: synaptics-rmi4: Limit the range of what GPIOs are buttons

[Andrew Duggan <aduggan@synaptics.com>]

By convention the first 6 bits of F30 Ctrl 2 and 3 are used to signify
GPIOs which are connected to buttons. Additional GPIOs may be used as
input GPIOs to signal the touch controller of some event
(ie disable touchpad). These additional GPIOs may meet the criteria of
a button in rmi_f30_is_valid_button() but should not be considered
buttons. This patch limits the GPIOs which are mapped to buttons to just
the first 6.

Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Reported-by: Daniel Martin <consume.noise@gmail.com>
---
I think that this patch will fix the issue with the Lenovo X1 Cover not
being set as a buttonpad. Based on the firmware config for this touchpad
there are additional GPIOs in Ctrl 2 and 3 position 6 and 7 unrelated to
buttons. This is confusing F30 into thinking there are additional buttons.

https://www.spinics.net/lists/linux-input/msg53626.html

 drivers/input/rmi4/rmi_f30.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/input/rmi4/rmi_f30.c b/drivers/input/rmi4/rmi_f30.c
index 34dfee5..a8ed424 100644
--- a/drivers/input/rmi4/rmi_f30.c
+++ b/drivers/input/rmi4/rmi_f30.c
@@ -232,9 +232,11 @@ static int rmi_f30_map_gpios(struct rmi_function *fn,
 	unsigned int trackstick_button = BTN_LEFT;
 	bool button_mapped = false;
 	int i;
+	int button_count = f30->gpioled_count > TRACKSTICK_RANGE_END
+				? TRACKSTICK_RANGE_END : f30->gpioled_count;
 
 	f30->gpioled_key_map = devm_kcalloc(&fn->dev,
-					    f30->gpioled_count,
+					    button_count,
 					    sizeof(f30->gpioled_key_map[0]),
 					    GFP_KERNEL);
 	if (!f30->gpioled_key_map) {
@@ -242,7 +244,7 @@ static int rmi_f30_map_gpios(struct rmi_function *fn,
 		return -ENOMEM;
 	}
 
-	for (i = 0; i < f30->gpioled_count; i++) {
+	for (i = 0; i < button_count; i++) {
 		if (!rmi_f30_is_valid_button(i, f30->ctrl))
 			continue;
 
-- 
2.7.4