[PATCH v5 6/7] Input: synaptics-rmi4 - read product ID on aftermarket touch ICs

[David Heidelberg via B4 Relay <devnull+david.ixit.cz@kernel.org>]

From: Kaustabh Chakraborty <kauschluss@disroot.org>

Some replacement displays include third-party touch ICs which do not
report the product ID correctly unless we read directly from the
product ID register. Add a check and a fallback read to handle this.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 drivers/input/rmi4/rmi_f01.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/input/rmi4/rmi_f01.c b/drivers/input/rmi4/rmi_f01.c
index 47be64284b25ede8103ada86d6b58fd3a26976bb..2278e9b6a920774b07ec9dd3e452cedc69469be8 100644
--- a/drivers/input/rmi4/rmi_f01.c
+++ b/drivers/input/rmi4/rmi_f01.c
@@ -250,6 +250,20 @@ static int rmi_f01_read_properties(struct rmi_device *rmi_dev,
 		}
 	}
 
+	/*
+	 * Some aftermarket ICs put garbage into the product id field unless
+	 * we read directly from the product id register.
+	 */
+	if (props->product_id[0] < 0x20) {
+		ret = rmi_read_block(rmi_dev, query_base_addr + 11,
+				       props->product_id, RMI_PRODUCT_ID_LENGTH);
+		if (ret) {
+			dev_err(&rmi_dev->dev,
+				"Failed to read product id: %d\n", ret);
+			return ret;
+		}
+	}
+
 	return 0;
 }
 

-- 
2.49.0