Skip to content

Commit

Permalink
power: supply: Fix logic checking if system is running from battery
Browse files Browse the repository at this point in the history
The logic used for power_supply_is_system_supplied() counts all power
supplies and assumes that the system is running from AC if there is
either a non-battery power-supply reporting to be online or if no
power-supplies exist at all.

The second rule is for desktop systems, that don't have any
battery/charger devices. These systems will incorrectly report to be
powered from battery once a device scope power-supply is registered
(e.g. a HID device), since these power-supplies increase the counter.

Apart from HID devices, recent dGPUs provide UCSI power supplies on a
desktop systems. The dGPU by default doesn't have anything plugged in so
it's 'offline'. This makes power_supply_is_system_supplied() return 0
with a count of 1 meaning all drivers that use this get a wrong judgement.

To fix this case adjust the logic to also examine the scope of the power
supply. If the power supply is deemed a device power supply, then don't
count it.

Cc: Evan Quan <Evan.Quan@amd.com>
Suggested-by: Lijo Lazar <Lijo.Lazar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
  • Loading branch information
Mario Limonciello authored and Sebastian Reichel committed May 16, 2023
1 parent 4cbb0d3 commit 95339f4
Showing 1 changed file with 6 additions and 2 deletions.
8 changes: 6 additions & 2 deletions drivers/power/supply/power_supply_core.c
Original file line number Diff line number Diff line change
Expand Up @@ -348,6 +348,10 @@ static int __power_supply_is_system_supplied(struct device *dev, void *data)
struct power_supply *psy = dev_get_drvdata(dev);
unsigned int *count = data;

if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_SCOPE, &ret))
if (ret.intval == POWER_SUPPLY_SCOPE_DEVICE)
return 0;

(*count)++;
if (psy->desc->type != POWER_SUPPLY_TYPE_BATTERY)
if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_ONLINE,
Expand All @@ -366,8 +370,8 @@ int power_supply_is_system_supplied(void)
__power_supply_is_system_supplied);

/*
* If no power class device was found at all, most probably we are
* running on a desktop system, so assume we are on mains power.
* If no system scope power class device was found at all, most probably we
* are running on a desktop system, so assume we are on mains power.
*/
if (count == 0)
return 1;
Expand Down

0 comments on commit 95339f4

Please sign in to comment.