1 files changed, 45 insertions, 12 deletions

diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 7a4a26b0edd2..899766e16fa8 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -5318,6 +5318,7 @@ static enum fan_control_commands fan_control_commands;
 
 static u8 fan_control_initial_status;
 static u8 fan_control_desired_level;
+static u8 fan_control_resume_level;
 static int fan_watchdog_maxinterval;
 
 static struct mutex fan_mutex;
@@ -5440,8 +5441,8 @@ static int fan_set_level(int level)
 
         case TPACPI_FAN_WR_ACPI_FANS:
         case TPACPI_FAN_WR_TPEC:
-                if ((level != TP_EC_FAN_AUTO) &&
-                    (level != TP_EC_FAN_FULLSPEED) &&
+                if (!(level & TP_EC_FAN_AUTO) &&
+                    !(level & TP_EC_FAN_FULLSPEED) &&
                     ((level < 0) || (level > 7)))
                         return -EINVAL;
 
@@ -6005,38 +6006,67 @@ static void fan_exit(void)
 
 static void fan_suspend(pm_message_t state)
 {
+        int rc;
+
         if (!fan_control_allowed)
                 return;
 
         /* Store fan status in cache */
-        fan_get_status_safe(NULL);
+        fan_control_resume_level = 0;
+        rc = fan_get_status_safe(&fan_control_resume_level);
+        if (rc < 0)
+                printk(TPACPI_NOTICE
+                        "failed to read fan level for later "
+                        "restore during resume: %d\n", rc);
+
+        /* if it is undefined, don't attempt to restore it.
+         * KEEP THIS LAST */
         if (tp_features.fan_ctrl_status_undef)
-                fan_control_desired_level = TP_EC_FAN_AUTO;
+                fan_control_resume_level = 0;
 }
 
 static void fan_resume(void)
 {
-        u8 saved_fan_level;
         u8 current_level = 7;
         bool do_set = false;
+        int rc;
 
         /* DSDT *always* updates status on resume */
         tp_features.fan_ctrl_status_undef = 0;
 
-        saved_fan_level = fan_control_desired_level;
         if (!fan_control_allowed ||
+            !fan_control_resume_level ||
             (fan_get_status_safe(&current_level) < 0))
                 return;
 
         switch (fan_control_access_mode) {
         case TPACPI_FAN_WR_ACPI_SFAN:
-                do_set = (saved_fan_level > current_level);
+                /* never decrease fan level */
+                do_set = (fan_control_resume_level > current_level);
                 break;
         case TPACPI_FAN_WR_ACPI_FANS:
         case TPACPI_FAN_WR_TPEC:
-                do_set = ((saved_fan_level & TP_EC_FAN_FULLSPEED) ||
-                          (saved_fan_level == 7 &&
-                           !(current_level & TP_EC_FAN_FULLSPEED)));
+                /* never decrease fan level, scale is:
+                 * TP_EC_FAN_FULLSPEED > 7 >= TP_EC_FAN_AUTO
+                 *
+                 * We expect the firmware to set either 7 or AUTO, but we
+                 * handle FULLSPEED out of paranoia.
+                 *
+                 * So, we can safely only restore FULLSPEED or 7, anything
+                 * else could slow the fan.  Restoring AUTO is useless, at
+                 * best that's exactly what the DSDT already set (it is the
+                 * slower it uses).
+                 *
+                 * Always keep in mind that the DSDT *will* have set the
+                 * fans to what the vendor supposes is the best level.  We
+                 * muck with it only to speed the fan up.
+                 */
+                if (fan_control_resume_level != 7 &&
+                    !(fan_control_resume_level & TP_EC_FAN_FULLSPEED))
+                        return;
+                else
+                        do_set = !(current_level & TP_EC_FAN_FULLSPEED) &&
+                                 (current_level != fan_control_resume_level);
                 break;
         default:
                 return;
@@ -6044,8 +6074,11 @@ static void fan_resume(void)
         if (do_set) {
                 printk(TPACPI_NOTICE
                         "restoring fan level to 0x%02x\n",
-                        saved_fan_level);
-                fan_set_level_safe(saved_fan_level);
+                        fan_control_resume_level);
+                rc = fan_set_level_safe(fan_control_resume_level);
+                if (rc < 0)
+                        printk(TPACPI_NOTICE
+                                "failed to restore fan level: %d\n", rc);
         }
 }