linux-kernel - [PATCH] Fix FSP-3Y YH-5151E non-compliant vout encoding

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Date:   Tue, 27 Apr 2021 15:58:06 +0200
From:   Václav Kubernát <kubernat@...net.cz>
To:     Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Václav Kubernát <kubernat@...net.cz>
Subject: [PATCH] Fix FSP-3Y YH-5151E non-compliant vout encoding

I didn't properly test the driver for the PDU, so it was completely
broken. Firstly, the log/real mapping was incorrect in one case.
Secondly, PMBus specifies that output voltages should be in the linear16
encoding. However, the PDU is non-compliant and uses linear11. The PSU
isn't affected by this.

pmbus_core didn't allow forcing linear11 format for output voltages, so
I added a way to force that.

Signed-off-by: Václav Kubernát <kubernat@...net.cz>
---
 drivers/hwmon/pmbus/fsp-3y.c     | 3 ++-
 drivers/hwmon/pmbus/pmbus.h      | 6 +++++-
 drivers/hwmon/pmbus/pmbus_core.c | 3 ++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pmbus/fsp-3y.c b/drivers/hwmon/pmbus/fsp-3y.c
index 564649e87e34..b4ea1e63272e 100644
--- a/drivers/hwmon/pmbus/fsp-3y.c
+++ b/drivers/hwmon/pmbus/fsp-3y.c
@@ -57,7 +57,7 @@ static int page_log_to_page_real(int page_log, enum chips chip)
 		case YH5151E_PAGE_12V_LOG:
 			return YH5151E_PAGE_12V_REAL;
 		case YH5151E_PAGE_5V_LOG:
-			return YH5151E_PAGE_5V_LOG;
+			return YH5151E_PAGE_5V_REAL;
 		case YH5151E_PAGE_3V3_LOG:
 			return YH5151E_PAGE_3V3_REAL;
 		}
@@ -164,6 +164,7 @@ struct pmbus_driver_info fsp3y_info[] = {
 	},
 	[yh5151e] = {
 		.pages = 3,
+		.format[PSC_VOLTAGE_OUT] = force_linear11,
 		.func[YH5151E_PAGE_12V_LOG] =
 			PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
 			PMBUS_HAVE_POUT  |
diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index 4c30ec89f5bf..4d79a43fc965 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -405,7 +405,11 @@ enum pmbus_sensor_classes {
 #define PMBUS_PHASE_VIRTUAL	BIT(30)	/* Phases on this page are virtual */
 #define PMBUS_PAGE_VIRTUAL	BIT(31)	/* Page is virtual */
 
-enum pmbus_data_format { linear = 0, direct, vid };
+/*
+ * force_linear11 is for non-compliant devices that output VOUT in linear11
+ * instead of linear16.
+ */
+enum pmbus_data_format { linear = 0, force_linear11, direct, vid };
 enum vrm_version { vr11 = 0, vr12, vr13, imvp9, amd625mv };
 
 struct pmbus_driver_info {
diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 192442b3b7a2..45a0d0303c19 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -589,7 +589,8 @@ static s64 pmbus_reg2data_linear(struct pmbus_data *data,
 	s32 mantissa;
 	s64 val;
 
-	if (sensor->class == PSC_VOLTAGE_OUT) {	/* LINEAR16 */
+	if (sensor->class == PSC_VOLTAGE_OUT &&	/* LINEAR16 */
+	    data->info->format[sensor->class] != force_linear11) {
 		exponent = data->exponent[sensor->page];
 		mantissa = (u16) sensor->data;
 	} else {				/* LINEAR11 */
-- 
2.31.1