Re: [PATCH 1/2] power: supply: Use the scope of power supplies to tell if power is system supplied

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On 5/16/2023 3:41 PM, Sebastian Reichel wrote:
Hi,

On Tue, May 16, 2023 at 01:25:40PM -0500, Mario Limonciello wrote:
The logic used for power_supply_is_system_supplied() counts all power
supplies and:
* If no power supplies found assumes AC
* If non-battery power supplies found uses online to determine AC/DC.
   - If any are onlined, assumes AC
   - Othewise DC.

This logic makes sense for desktop systems that don't export an ACPI
battery, but it fails once you include a dGPU that provides a UCSI
power supply on a desktop system without any other power supplies.

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@xxxxxxx>
Suggested-by: Lijo Lazar <Lijo.Lazar@xxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
Good find; the current logic should also break with a desktop PC
once a POWER_SUPPLY_SCOPE_DEVICE battery device is attached (e.g.
a HID device), because it increases the counter.

Yup!

I suppose I can just apply this to my fixes branch since there is
no compile time dependency to the second patch?

Yes, that's correct.  I don't see a problem with the other patch going through
another tree.

-- Sebastian

  drivers/power/supply/power_supply_core.c | 8 ++++++--
  1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index ab986dbace16..d57f420ba8c3 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -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,
@@ -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;
--
2.34.1




[Index of Archives]     [Linux GPIO]     [Linux SPI]     [Linux Hardward Monitoring]     [LM Sensors]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux