On 10/18/2013 07:56 PM, Kirill Tkhai wrote: > On HP 250 G1 laptops, BIOS reports minimum backlight on boot and > causes backlight to dim completely. This ignores the initial backlight > values and set to max brightness. > > Reference: https://bugzilla.kernel.org/show_bug.cgi?id=63111 According to the acpidump: The ASL code initialize initial brightness level to 100, but only for OS that is pre-vista. Don't know why it does this... Method (_INI, 0, NotSerialized) // _INI: Initialize { If (LLess (OSYS, 0x07D6)) { Store (0x64, BRTL) } ... ... } Method (_BQC, 0, NotSerialized) // _BQC: Brightness Query Current { Return (BRTL) } Since it is not initialized in _INI(as we report to firmware we are 'Windows 2012'), the video module was told by _BQC the initial brightness level is 0 and then set backlight level to 0 and leads to a black screen after boot up. > Signed-off-by: Kirill Tkhai <tkhai@xxxxxxxxx> The patch looks good to me. Reviewed-by: Aaron Lu <aaron.lu@xxxxxxxxx> Thanks, Aaron > --- > drivers/acpi/video.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c > index 3270d3c..6456466 100644 > --- a/drivers/acpi/video.c > +++ b/drivers/acpi/video.c > @@ -490,6 +490,14 @@ static struct dmi_system_id video_dmi_table[] __initdata = { > DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion m4 Notebook PC"), > }, > }, > + { > + .callback = video_ignore_initial_backlight, > + .ident = "HP 250 G1", > + .matches = { > + DMI_MATCH(DMI_BOARD_VENDOR, "Hewlett-Packard"), > + DMI_MATCH(DMI_PRODUCT_NAME, "HP 250 G1 Notebook PC"), > + }, > + }, > {} > }; > > -- > 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 > -- 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
