linux-kernel - [PATCH v3] usb: typec: ucsi: Use GET_CAPABILITY attributes data to set power supply scope

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Message-ID: <20231009184643.129986-1-mario.limonciello@amd.com>
Date:   Mon, 9 Oct 2023 13:46:43 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     <heikki.krogerus@...ux.intel.com>, <gregkh@...uxfoundation.org>
CC:     <wsa@...nel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <Alexander.Deucher@....com>,
        <Richard.Gong@....com>, <kai.heng.feng@...onical.com>,
        <sebastian.reichel@...labora.com>,
        Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH v3] usb: typec: ucsi: Use GET_CAPABILITY attributes data to set power supply scope

On some OEM systems, adding a W7900 dGPU triggers RAS errors and hangs
at a black screen on startup.  This issue occurs only if `ucsi_acpi` has
loaded before `amdgpu` has loaded.  The reason for this failure is that
`amdgpu` uses power_supply_is_system_supplied() to determine if running
on AC or DC power at startup. If this value is reported incorrectly the
dGPU will also be programmed incorrectly and trigger errors.

power_supply_is_system_supplied() reports the wrong value because UCSI
power supplies provided as part of the system don't properly report the
scope as "DEVICE" scope (not powering the system).

In order to fix this issue check the capabilities reported from the UCSI
power supply to ensure that it supports charging a battery and that it can
be powered by AC.  Mark the scope accordingly.

Cc: stable@...r.kernel.org
Fixes: a7fbfd44c020 ("usb: typec: ucsi: Mark dGPUs as DEVICE scope")
Link: https://www.intel.com/content/www/us/en/products/docs/io/universal-serial-bus/usb-type-c-ucsi-spec.html p28
Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
Cc: Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc: Alex Deucher <Alexander.Deucher@....com>>
Cc: Richard Gong <Richard.Gong@....com>

v2->v3:
 * Pick up tag
 * Add missing stable tag
 * Drop patch 2, we'll just avoid upstreaming it.
---
 drivers/usb/typec/ucsi/psy.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/typec/ucsi/psy.c b/drivers/usb/typec/ucsi/psy.c
index 384b42267f1f..b35c6e07911e 100644
--- a/drivers/usb/typec/ucsi/psy.c
+++ b/drivers/usb/typec/ucsi/psy.c
@@ -37,6 +37,15 @@ static int ucsi_psy_get_scope(struct ucsi_connector *con,
 	struct device *dev = con->ucsi->dev;
 
 	device_property_read_u8(dev, "scope", &scope);
+	if (scope == POWER_SUPPLY_SCOPE_UNKNOWN) {
+		u32 mask = UCSI_CAP_ATTR_POWER_AC_SUPPLY |
+			   UCSI_CAP_ATTR_BATTERY_CHARGING;
+
+		if (con->ucsi->cap.attributes & mask)
+			scope = POWER_SUPPLY_SCOPE_SYSTEM;
+		else
+			scope = POWER_SUPPLY_SCOPE_DEVICE;
+	}
 	val->intval = scope;
 	return 0;
 }
-- 
2.34.1