[PATCH] Input: tca8418_keypad - enable overflow mode per datasheet (SCPS215G)

[PATCH] Input: tca8418_keypad - enable overflow mode per datasheet (SCPS215G)

[Zhian Liang]

The driver currently sets only the overflow interrupt enable bit
(OVR_FLOW_IEN) in the configuration register, leaving the overflow
mode bit (OVR_FLOW_M) at its default value of 0.

According to the TCA8418 datasheet (SCPS215G, Section 8.6.4.1
"Overflow Errata - Description"), both OVR_FLOW_M (Bit_5) and
OVR_FLOW_IEN (Bit_3) must be set high for the overflow interrupt
to be generated. If only OVR_FLOW_IEN is set, FIFO overflow events
are silently lost without notifying the host.

Fix this by setting OVR_FLOW_M alongside OVR_FLOW_IEN in the
configuration register.

Note: I do not have access to hardware to test this change.
Testing by generating 11+ key events without reading the FIFO
would be appreciated. Full handling of overflow events in the
interrupt handler is left for future improvement.

Signed-off-by: Zhian Liang <liangzhan5dev@gmail.com>
---
 drivers/input/keyboard/tca8418_keypad.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/tca8418_keypad.c b/drivers/input/keyboard/tca8418_keypad.c
index 68c0afafee7b..b124e576feca 100644
--- a/drivers/input/keyboard/tca8418_keypad.c
+++ b/drivers/input/keyboard/tca8418_keypad.c
@@ -254,7 +254,7 @@ static int tca8418_configure(struct tca8418_keypad *keypad_data,
 		return error;
 
 	error = tca8418_write_byte(keypad_data, REG_CFG,
-				CFG_INT_CFG | CFG_OVR_FLOW_IEN | CFG_KE_IEN);
+				CFG_INT_CFG | CFG_OVR_FLOW_IEN | CFG_OVR_FLOW_M | CFG_KE_IEN);
 
 	return error;
 }
-- 
2.34.1

Re: [PATCH] Input: tca8418_keypad - enable overflow mode per datasheet (SCPS215G)

[Dmitry Torokhov]

On Fri, May 29, 2026 at 09:39:00AM +0800, Zhian Liang wrote:
> The driver currently sets only the overflow interrupt enable bit
> (OVR_FLOW_IEN) in the configuration register, leaving the overflow
> mode bit (OVR_FLOW_M) at its default value of 0.
> 
> According to the TCA8418 datasheet (SCPS215G, Section 8.6.4.1
> "Overflow Errata - Description"), both OVR_FLOW_M (Bit_5) and
> OVR_FLOW_IEN (Bit_3) must be set high for the overflow interrupt
> to be generated. If only OVR_FLOW_IEN is set, FIFO overflow events
> are silently lost without notifying the host.
> 
> Fix this by setting OVR_FLOW_M alongside OVR_FLOW_IEN in the
> configuration register.
> 
> Note: I do not have access to hardware to test this change.
> Testing by generating 11+ key events without reading the FIFO
> would be appreciated. Full handling of overflow events in the
> interrupt handler is left for future improvement.
> 
> Signed-off-by: Zhian Liang <liangzhan5dev@gmail.com>

Applied, thank you.

-- 
Dmitry