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

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

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@vger.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@collabora.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
> Cc: Alex Deucher <Alexander.Deucher@amd.com>>
> Cc: Richard Gong <Richard.Gong@amd.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

-- 
heikki