Hi Dan, 於 四，2012-09-27 於 14:09 -0400，Dan 提到： > On Wed, Sep 26, 2012 at 7:19 PM, joeyli <jlee@xxxxxxxx> wrote: > > 於 三，2012-09-26 於 16:48 -0400，Dan 提到： > >> Hello, > >> > >> Apologies if this was sent to the wrong place. > >> > >> With an Acer AOD255E netbook, the backlight goes out for exactly 10 > >> seconds before returning while booting. > >> > >> This is a backlight issue and not KMS, as I can shine a flashlight at > >> the screen and still see boot text scrolling. > >> > >> With "acpi=off" appended to the kernel line, this no longer occurs (Fn > >> key backlight controls still work with this appended). With every It's a clue for that problem is happen in acpi, but sometimes the Fn key on notebook is changed by BIOS, need check DSDT. > >> other acpi option I have tried, this still occurs though. This > >> includes "acpi_backlight" and "acpi_display_output". With > >> "acpi_backlight=vendor" the entry in /sys/class/backlight changes from > >> acpi_video0 to acer_wmi, but backlight still goes out. > >> > >> Otherwise backlight works correctly. > > > > Could you please try this kernel parameter? > > video.use_bios_initial_backlight=0 > > > > > > Thanks > > Joey Lee > > > > Same results with that kernel parameter applied. > This parameter works when _BQC used indexed value but not direct use brightness value. One possible thing is BIOS really set the initial index or brightness level to lowest level. > Just to make it clear when this is happening: > The BIOS screen and bootloader work fine. This occurs during the boot > process while the systemd text is scrolling (or with the splash screen > in the case of Ubuntu). I have not been able to pin down any event > during the boot process that triggers it. It seems to be based on time > after the kernel loads. I can tell by the difference booting from a > HDD vs a SSD. With a HDD, it will occur earlier in the process (close > to the time init is called) since booting takes longer. With an SSD, > the backlight goes out close to the time the login screen appears. > > Once the backlight is out, it will stay out for exactly 10 seconds > before returning no matter what is on the screen. > What's your value of max brightness? Please run: # cat /sys/class/backlight/acpi_video0/max_brightness Please also manually change brightness level after your system boot finished, and look at does it changed or have problem like reversed? # echo 10 > /sys/class/backlight/acpi_video0/brightness And, Please attached your acpidump: # acpidump > acpidump.dat Thanks Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
