[PATCH v9 4/5] Input: synaptics-rmi4 - read product ID on aftermarket touch ICs

From: Kaustabh Chakraborty <[email protected]>

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 <[email protected]>
Signed-off-by: Casey Connolly <[email protected]>
Signed-off-by: David Heidelberg <[email protected]>
---
 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 47be64284b25e..2278e9b6a9207 100644
--- a/drivers/input/rmi4/rmi_f01.c
+++ b/drivers/input/rmi4/rmi_f01.c
@@ -245,16 +245,30 @@ static int rmi_f01_read_properties(struct rmi_device *rmi_dev,
 				return ret;
 			}
 
 			props->firmware_id = queries[1] << 8 | queries[0];
 			props->firmware_id += queries[2] * 65536;
 		}
 	}
 
+	/*
+	 * 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;
 }
 
 const char *rmi_f01_get_product_ID(struct rmi_function *fn)
 {
 	struct f01_data *f01 = dev_get_drvdata(&fn->dev);
 
 	return f01->properties.product_id;

-- 
2.53.0