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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2016-10-04 13:51:40 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-10-10 02:20:43 +0200
commit84baf1725dc532d9746df2d216c1921154767109 (patch)
tree764c9d49ecfc2d33c5c195b91c2bdaff584ab830
parentc8d2bc9bc39ebea8437fd974fdbc21847bb897a3 (diff)
ACPI / fan: Fix error reading cur_state
On some platforms with ACPI4 variable speed fan, reading cur_state from cooling device returns "invalid value" error. This confuses user space applications. This issue occurs as the current driver doesn't take account of "FineGrainControl" from _FIF(Fan Information). When the "FineGrainControl" is set, _FSL(FSL Set Level) takes argument as a percent, which doesn't have to match from any control value from _FPS(Fan Performance States). It is also possible that the Fan is not actually running at the requested speed returning a lower speed. On some platforms the BIOS is setting fan speed to a level during boot, which will not have an exact match to _FPS control values. The current implementation will treat this level as invalid value. The simple change is to atleast return state corresponding to a maximum control value in the _FPS compared to the current level. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--drivers/acpi/fan.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c
index 384cfc3083e1..6cf4988206f2 100644
--- a/drivers/acpi/fan.c
+++ b/drivers/acpi/fan.c
@@ -129,8 +129,18 @@ static int fan_get_state_acpi4(struct acpi_device *device, unsigned long *state)
control = obj->package.elements[1].integer.value;
for (i = 0; i < fan->fps_count; i++) {
- if (control == fan->fps[i].control)
+ /*
+ * When Fine Grain Control is set, return the state
+ * corresponding to maximum fan->fps[i].control
+ * value compared to the current speed. Here the
+ * fan->fps[] is sorted array with increasing speed.
+ */
+ if (fan->fif.fine_grain_ctrl && control < fan->fps[i].control) {
+ i = (i > 0) ? i - 1 : 0;
break;
+ } else if (control == fan->fps[i].control) {
+ break;
+ }
}
if (i == fan->fps_count) {
dev_dbg(&device->dev, "Invalid control value returned\n");