On Tue, Dec 5, 2017 at 6:40 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi Chris, > > On 30-11-17 07:27, Chris Chiu wrote: >> >> Hi, >> I have a Intel cherry trail machine Haier HR101CW (CPU: x5-Z8350) >> which used to work fine in kernel 4.11, fails to enter X after I >> upgrade to kernel version later than 4.12. Even the latest 4.15, it >> can't even enter X now. There's no panic, oops and even no obvious >> error log. The panel backlight seems to be off but keyboard still >> responds. >> >> Then I tried to do bisect, it tells me the commit >> [b7ecf663c75eed1e764f57281f9508c49c18516e] ACPI / bus: Introduce a >> list of ids for "always present" devices is the one which causes this. >> After I revert this commit, the display back to normal. >> >> Maybe the DSDT file would help for your reference. >> https://gist.github.com/mschiu77/e84687cc928ac644117baf05aef47f16 > > > Hmm, Daniel Drake from Endless send me a Vios LTH17 machine which > has similar symptoms. If this is indeed the same issue then adding: > i915.fastboot=1 to the kernel commandline should fix this. > > This is going to be the default for newer kernels soon-ish (4.16 > I think), so we can use this as a workaround for now. > > As for the commit you bisected this to, can you try just commenting > out the: "80862288" entry in always_present_ids in > drivers/acpi/x86/utils.c ? I think that is triggering the problem. > > Without that entry we don't get backlight control, so if you > comment it you will likely not be able to control brightness, > so i915.fastboot=1 is a better fix, but it would be good to know > if commenting out just that entry fixes things (and breaks > brightness control). > > Without i915.fastboot=1 the i915 driver quickly turns the > backlight off and on again at boot, which I guess is confusing > the LCD panel... > > Regards, > > Hans > Hmm...the i915.fastboot=1 seems not work on my Haier machine here. However, comment out the: "80862288" entry in always_present_ids in drivers/acpi/x86/utils.c do work. Do you need anything on this special machine? Chris -- 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
