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

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Message-ID: <1e8c1db9-5d52-4b39-8bdf-7d7d70ed1157@amd.com>
Date:   Tue, 10 Oct 2023 12:49:35 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Greg Kroah-Hartman <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,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v3] usb: typec: ucsi: Use GET_CAPABILITY attributes data
 to set power supply scope

On 10/10/2023 03:42, Heikki Krogerus wrote:
> On Mon, Oct 09, 2023 at 01:46:43PM -0500, Mario Limonciello wrote:
>> 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>
> 
> Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

Thanks!

Greg, this behavior is pretty awful with the hang at bootup on these OEM 
systems, do you think this can come into one of the 6.6-rcX or should it 
wait until 6.7?

> 
>> ---
>> 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
>