This occurs when starting up b2g on Nexus 5. I haven't tested Flame (yet). Problem is in gecko/hal/gonk/GonkHal.cpp. It appears that GetKeyLightEnabled() returns an undefined value. It looks like this: bool GetKeyLightEnabled() { LightConfiguration config; GetLight(hal::eHalLightID_Buttons, &config); return (config.color != 0x00000000); } The call to GetLight is intended to write values into |config|, but in fact GetLight returns a |bool| indicating success/failure, which this routine ignores. So it just assumes that |config| got filled in, which isn't true. There's a second call point in this file to GetLight, that also ignores the return result, in GetScreenBrightness.

Adds (ultra-trivial) handling of failure of GetLight(). mwu, what are suitable values for GetKeyLightEnabled() and GetScreenBrightness() in case of failure of GetLight() ?

Comment on attachment 8610580 [details] [diff] [review] bug1125084-1.diff Review of attachment 8610580 [details] [diff] [review]: ----------------------------------------------------------------- ::: hal/gonk/GonkHal.cpp @@ +767,5 @@ > + bool ok = GetLight(eHalLightID_Buttons, &config); > + if (ok) { > + return (config.color != 0x00000000); > + } else { > + return false; This seems ok to me. @@ +807,5 @@ > + // backlight is brightness only, so using one of the RGB elements as value. > + int brightness = config.color & 0xFF; > + return brightness / 255.0; > + } else { > + return 0.5; The right thing to do here might be to crash. Alternately, we can cache the last brightness setting and return that.

Comment on attachment 8610580 [details] [diff] [review] bug1125084-1.diff Review of attachment 8610580 [details] [diff] [review]: ----------------------------------------------------------------- Just a couple minor nits. ::: hal/gonk/GonkHal.cpp @@ +766,5 @@ > LightConfiguration config; > + bool ok = GetLight(eHalLightID_Buttons, &config); > + if (ok) { > + return (config.color != 0x00000000); > + } else { nit: lose the else, unindent the return @@ +806,5 @@ > + if (ok) { > + // backlight is brightness only, so using one of the RGB elements as value. > + int brightness = config.color & 0xFF; > + return brightness / 255.0; > + } else { nit: lose the else @@ +807,5 @@ > + // backlight is brightness only, so using one of the RGB elements as value. > + int brightness = config.color & 0xFF; > + return brightness / 255.0; > + } else { > + return 0.5; I think that if GetLight fails, then its because that light doesn't exist, so returning a cached value doesn't make sense. I think I'd just return 0 (or whatever value corresponds to off).

Addresses review comments in comment 3 and comment 4.

Comment on attachment 8612263 [details] [diff] [review] bug1125084-2.diff Review of attachment 8612263 [details] [diff] [review]: ----------------------------------------------------------------- lgtm