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From: Guenter Roeck <linux@roeck-us.net>
To: linux-hwmon@vger.kernel.org
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Yo-Jung Lin <leo.lin@canonical.com>,
	Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH 2/5] hwmon: (spd5118) Name chips taking the specification literally
Date: Sat, 19 Apr 2025 09:13:52 -0700	[thread overview]
Message-ID: <20250419161356.2528986-3-linux@roeck-us.net> (raw)
In-Reply-To: <20250419161356.2528986-1-linux@roeck-us.net>

The Renesas/IDT SPD5118 Hub Controller is known to take the specification
literally and does not permit access to volatile registers except for the
page register if the selected page is non-zero. Explicitly name the chip
to ensure that the information does not get lost.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/spd5118.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
index 02eb21684c3a..c5ad06b90cbf 100644
--- a/drivers/hwmon/spd5118.c
+++ b/drivers/hwmon/spd5118.c
@@ -621,7 +621,8 @@ static int spd5118_i2c_init(struct i2c_client *client)
 	 * If the device type registers return 0, it is possible that the chip
 	 * has a non-zero page selected and takes the specification literally,
 	 * i.e. disables access to volatile registers besides the page register
-	 * if the page is not 0. Try to identify such chips.
+	 * if the page is not 0. The Renesas/ITD SPD5118 Hub Controller is known
+	 * to show this behavior. Try to identify such chips.
 	 */
 	if (!regval) {
 		/* Vendor ID registers must also be 0 */
-- 
2.45.2


  parent reply	other threads:[~2025-04-19 16:14 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-19 16:13 [PATCH 0/5] hwmon: (spd5118) Add I3C support Guenter Roeck
2025-04-19 16:13 ` [PATCH 1/5] hwmon: (spd5118) Split into common and I2C specific code Guenter Roeck
2025-04-19 16:13 ` Guenter Roeck [this message]
2025-04-19 16:13 ` [PATCH 3/5] hwmon: (spd5118) Support 16-bit addressing for NVMEM accesses Guenter Roeck
2025-04-19 16:13 ` [PATCH 4/5] hwmon: (spd5118) Detect and support 16-bit register addressing Guenter Roeck
2025-04-19 16:13 ` [RFT PATCH 5/5] hwmon: (spd5118) Add I3C support Guenter Roeck

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