thinkpad-acpi: document backlight level writeback at driver init

Document this, it is no fun to try to second guess why this sort of
stuff is in place years after it was added...

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index b3bfce9538386dd9f4277c525cc0adf68b5fb574..4bdb13796e24eba6b494f1cd9ad315b1072652c1 100644 (file)
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6397,6 +6397,10 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
                        "or not on your ThinkPad\n", TPACPI_MAIL);
        }
 
+       /* Added by mistake in early 2007.  Probably useless, but it could
+        * be working around some unknown firmware problem where the value
+        * read at startup doesn't match the real hardware state... so leave
+        * it in place just in case */
        backlight_update_status(ibm_backlight_device);
 
        vdbg_printk(TPACPI_DBG_INIT | TPACPI_DBG_BRGHT,