linux-kernel - Re: [PATCH 2/3] power: supply: Don't count 'unknown' scope power supplies

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Message-ID: <20230930201826.biy27esyw4ttxt4p@mercury.elektranox.org>
Date:   Sat, 30 Sep 2023 22:18:26 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     amd-gfx@...ts.freedesktop.org,
        Alex Deucher <alexander.deucher@....com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jun.ma2@....com
Subject: Re: [PATCH 2/3] power: supply: Don't count 'unknown' scope power
 supplies

Hi,

On Tue, Sep 26, 2023 at 05:59:54PM -0500, Mario Limonciello wrote:
> On some systems AMD Navi3x dGPU triggers RAS errors on startup; but
> only if the amdgpu kernel module is not part of the initramfs.
> This is because the hardware is not properly programmed for the
> AC/DC state of the system when it is loaded later in boot.

I don't understand the last sentence. As far as I can see
i2c_dw_pci_probe() either does not registers UCSI at all or
with the dGPU properties (and thus scope) set.

> The AC/DC state of the system is incorrect specifically when UCSI power
> supplies have been initialized.  These power supplies are marked as
> POWER_SUPPLY_SCOPE_UNKNOWN scope. As they're 'offline' the power
> supply count is increased but the resultant return value is
> power_supply_is_system_supplied() 0.
> 
> To fix this look explicitly for `POWER_SUPPLY_SCOPE_SYSTEM` power
> supplies before incrementing the count. If no system power supply
> is found then the system is assumed to be on AC.
> 
> Cc: stable@...r.kernel.org
> Tested-by: David Perry <David.Perry@....com>
> Fixes: 95339f40a8b6 ("power: supply: Fix logic checking if system is running from battery")
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---

This effectively fully disables supply detection for UCSI, because
it is never set to POWER_SUPPLY_SCOPE_SYSTEM. Please fix the amdgpu
init part instead.

-- Sebastian

>  drivers/power/supply/power_supply_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> index d325e6dbc770..3de6e6d00815 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -349,7 +349,7 @@ static int __power_supply_is_system_supplied(struct device *dev, void *data)
>  	unsigned int *count = data;
>  
>  	if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_SCOPE, &ret))
> -		if (ret.intval == POWER_SUPPLY_SCOPE_DEVICE)
> +		if (ret.intval != POWER_SUPPLY_SCOPE_SYSTEM)
>  			return 0;
>  
>  	(*count)++;
> -- 
> 2.34.1
> 

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