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From: "Pradhan, Sanman" <sanman.pradhan@hpe.com>
To: Guenter Roeck <linux@roeck-us.net>,
	Jonathan Corbet <corbet@lwn.net>, "Rob Herring" <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>
Cc: "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Sanman Pradhan <psanman@juniper.net>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: [PATCH 1/3] hwmon: (pmbus/tps53679) Fix TPS53676 phase page decoding
Date: Fri, 4 Sep 2026 22:08:56 +0000	[thread overview]
Message-ID: <20260904220843.495082-2-sanman.pradhan@hpe.com> (raw)
In-Reply-To: <20260904220843.495082-1-sanman.pradhan@hpe.com>

From: Sanman Pradhan <psanman@juniper.net>

tps53676_identify() reads the USER_DATA_03 phase configuration to count
the phases assigned to each channel and derive the number of PMBus pages.
In each 16-bit phase descriptor the channel (PAGE) is encoded in bit 4 and
the firing order in bits 3:0, but the code tested bit 3 (0x08), which is
part of the firing-order field.

TPS53676 supports up to seven phases, so firing-order bit 3 is never set.
As a result the existing test classifies every enabled phase as channel A.
On a dual-channel configuration the phases assigned to channel B are
therefore miscounted as channel A and page 1 is not exposed.

Test the PAGE field (bit 4) instead.

Fixes: cb3d37b59012 ("hwmon: (pmbus/tps53679) Add support for TI TPS53676")
Cc: stable@vger.kernel.org
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
---
 drivers/hwmon/pmbus/tps53679.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/tps53679.c b/drivers/hwmon/pmbus/tps53679.c
index fa0fdf1e3e6c9..680339a6b90fe 100644
--- a/drivers/hwmon/pmbus/tps53679.c
+++ b/drivers/hwmon/pmbus/tps53679.c
@@ -188,7 +188,7 @@ static int tps53676_identify(struct i2c_client *client,
 		return -EIO;
 	for (i = 0; i < 2 * TPS53676_MAX_PHASES; i += 2) {
 		if (buf[i + 1] & 0x80) {
-			if (buf[i] & 0x08)
+			if (buf[i] & BIT(4))
 				phases_b++;
 			else
 				phases_a++;
-- 
2.34.1


  reply	other threads:[~2026-09-04 22:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-04 22:08 [PATCH 0/3] hwmon: (pmbus/tps53679) Add TPS536C7 Pradhan, Sanman
2026-09-04 22:08 ` Pradhan, Sanman [this message]
2026-09-04 22:09 ` [PATCH 2/3] dt-bindings: trivial-devices: Add TI TPS536C7 Pradhan, Sanman
2026-09-04 22:09 ` [PATCH] hwmon: (pmbus/tps53679) Add support for TPS536C7 Pradhan, Sanman

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