linux-kernel - [PATCH v3 6/7] Input: synaptics-rmi4 - read product ID on aftermarket touch ICs

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Message-Id: <20250308-synaptics-rmi4-v3-6-215d3e7289a2@ixit.cz>
Date: Sat, 08 Mar 2025 15:08:42 +0100
From: David Heidelberg via B4 Relay <devnull+david.ixit.cz@...nel.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, "Jason A. Donenfeld" <Jason@...c4.com>, 
 Matthias Schiffer <matthias.schiffer@...tq-group.com>, 
 Vincent Huang <vincent.huang@...synaptics.com>
Cc: linux-input@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org, 
 ~postmarketos/upstreaming@...ts.sr.ht, methanal <baclofen@...a.io>, 
 Caleb Connolly <caleb.connolly@...aro.org>
Subject: [PATCH v3 6/7] Input: synaptics-rmi4 - read product ID on
 aftermarket touch ICs

From: methanal <baclofen@...a.io>

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: methanal <baclofen@...a.io>
Signed-off-by: Caleb Connolly <caleb.connolly@...aro.org>
---
 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;
 }

-- 
2.47.2