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authorArmin Wolf <W_Armin@gmx.de>2023-03-24 23:26:28 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2023-03-30 20:01:05 +0300
commit3bd554e03ef412438b42862cb088ddc4e2a2561b (patch)
treee1fcda5c8f62dbbd24f89418f16caf9c3f5758bc
parente5b492c6bb900fcf9722e05f4a10924410e170c1 (diff)
downloadlinux-3bd554e03ef412438b42862cb088ddc4e2a2561b.tar.xz
ACPI: SBS: Fix handling of Smart Battery Selectors
The "Smart Battery Selector" standard says that when writing SelectorState (0x1), the nibbles which should not be modified need to be masked with 0xff. This is necessary since in contrast to a "Smart Battery Manager", the last three nibbles are writable. Failing to do so might trigger the following cycle: 1. Host accidentally changes power source of the system (3rd nibble) when selecting a battery. 2. Power source is invalid, Selector changes to another power source. 3. Selector notifies host that it changed the power source. 4. Host re-reads some batteries. 5. goto 1 for each re-read battery. This loop might also be entered when a battery which is not present is selected for SMBus access. In the end some workqueues fill up, which causes the system to lockup upon suspend/shutdown. Fix this by correctly masking the value to be written, and avoid selecting batteries which are absent. Tested on a Acer Travelmate 4002WLMi. Signed-off-by: Armin Wolf <W_Armin@gmx.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--drivers/acpi/sbs.c27
1 files changed, 18 insertions, 9 deletions
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index e90752d4f488..94e3c000df2e 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -473,23 +473,32 @@ static const struct device_attribute alarm_attr = {
-------------------------------------------------------------------------- */
static int acpi_battery_read(struct acpi_battery *battery)
{
- int result = 0, saved_present = battery->present;
+ int result, saved_present = battery->present;
u16 state;
if (battery->sbs->manager_present) {
result = acpi_smbus_read(battery->sbs->hc, SMBUS_READ_WORD,
ACPI_SBS_MANAGER, 0x01, (u8 *)&state);
- if (!result)
- battery->present = state & (1 << battery->id);
- state &= 0x0fff;
+ if (result)
+ return result;
+
+ battery->present = state & (1 << battery->id);
+ if (!battery->present)
+ return 0;
+
+ /* Masking necessary for Smart Battery Selectors */
+ state = 0x0fff;
state |= 1 << (battery->id + 12);
acpi_smbus_write(battery->sbs->hc, SMBUS_WRITE_WORD,
ACPI_SBS_MANAGER, 0x01, (u8 *)&state, 2);
- } else if (battery->id == 0)
- battery->present = 1;
-
- if (result || !battery->present)
- return result;
+ } else {
+ if (battery->id == 0) {
+ battery->present = 1;
+ } else {
+ if (!battery->present)
+ return 0;
+ }
+ }
if (saved_present != battery->present) {
battery->update_time = 0;