sony-laptop: warn on multiple KBD backlight handles

Some BIOS versions/Vaio models apparently ship with two nearly identical
functions to handle backlight related controls.
The only difference seems to be:
        If (LEqual (BUF1, 0x40))
        {
            Store (0x40, P80H)
            Store (BUF2, Local0)
-           And (Local0, One, Local0)
+           And (Local0, 0x03, Local0)
            Store (Local0, ^^H_EC.KLPC)
        }

Avoid erroring out on initialization and messing things up on cleanup
for now since we never call into these methods with anything different
than 1 or 0.
This issue was found on a Sony VPCSE1V9E/BIOS R2087H4.

Cc: Marco Krüger <krgsch@gmail.com>
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 47caab0ea7a1..03f02cc476e5 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -145,7 +145,8 @@ static void sony_nc_thermal_resume(void);
 #endif
 static int sony_nc_kbd_backlight_setup(struct platform_device *pd,
                 unsigned int handle);
-static void sony_nc_kbd_backlight_cleanup(struct platform_device *pd);
+static void sony_nc_kbd_backlight_cleanup(struct platform_device *pd,
+                unsigned int handle);
 
 static int sony_nc_battery_care_setup(struct platform_device *pd,
                 unsigned int handle);
@@ -1444,7 +1445,7 @@ static void sony_nc_function_cleanup(struct platform_device *pd)
                 case 0x014b:
                 case 0x014c:
                 case 0x0163:
-                        sony_nc_kbd_backlight_cleanup(pd);
+                        sony_nc_kbd_backlight_cleanup(pd, handle);
                         break;
                 default:
                         continue;
@@ -1822,6 +1823,12 @@ static int sony_nc_kbd_backlight_setup(struct platform_device *pd,
         int result;
         int ret = 0;
 
+        if (kbdbl_ctl) {
+                pr_warn("handle 0x%.4x: keyboard backlight setup already done for 0x%.4x\n",
+                                handle, kbdbl_ctl->handle);
+                return -EBUSY;
+        }
+
         /* verify the kbd backlight presence, these handles are not used for
          * keyboard backlight only
          */
@@ -1881,9 +1888,10 @@ outkzalloc:
         return ret;
 }
 
-static void sony_nc_kbd_backlight_cleanup(struct platform_device *pd)
+static void sony_nc_kbd_backlight_cleanup(struct platform_device *pd,
+                unsigned int handle)
 {
-        if (kbdbl_ctl) {
+        if (kbdbl_ctl && handle == kbdbl_ctl->handle) {
                 device_remove_file(&pd->dev, &kbdbl_ctl->mode_attr);
                 device_remove_file(&pd->dev, &kbdbl_ctl->timeout_attr);
                 kfree(kbdbl_ctl);