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[v4,4/7] Input: synaptics-rmi4 - f55: handle zero electrode count

Message ID 20250402-synaptics-rmi4-v4-4-1bb95959e564@ixit.cz (mailing list archive)
State New
Headers show
Series Input: synaptics-rmi4 - add quirks for third party touchscreen controllers | expand

Commit Message

David Heidelberg April 2, 2025, 6:44 p.m. UTC 
From: Kaustabh Chakraborty <kauschluss@disroot.org>

Some third party ICs claim to support f55 but report an electrode count
of 0. Catch this and bail out early so that we don't confuse the i2c bus
with 0 sized reads.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
[simplify code, adjust wording]
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 drivers/input/rmi4/rmi_f55.c | 5 +++++
 1 file changed, 5 insertions(+)
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Patch

diff --git a/drivers/input/rmi4/rmi_f55.c b/drivers/input/rmi4/rmi_f55.c
index 488adaca4dd00482cd1106d813b32871092c83a0..776c915b82e72b8a6eb5ec701cce9059c87089c4 100644
--- a/drivers/input/rmi4/rmi_f55.c
+++ b/drivers/input/rmi4/rmi_f55.c
@@ -52,6 +52,11 @@  static int rmi_f55_detect(struct rmi_function *fn)
 
 	f55->num_rx_electrodes = f55->qry[F55_NUM_RX_OFFSET];
 	f55->num_tx_electrodes = f55->qry[F55_NUM_TX_OFFSET];
+	if (!f55->num_rx_electrodes || !f55->num_tx_electrodes) {
+		dev_err(&fn->dev, "%s: F55 query returned no electrodes, giving up\n",
+			__func__);
+		return -EINVAL;
+	}
 
 	f55->cfg_num_rx_electrodes = f55->num_rx_electrodes;
 	f55->cfg_num_tx_electrodes = f55->num_rx_electrodes;