On 08/04/2013 10:19 PM, Felipe Contreras wrote: > On Sun, Aug 4, 2013 at 9:19 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: >> On Sunday, August 04, 2013 01:42:49 AM Felipe Contreras wrote: > >>> Personally I think there are better ways to fix the code for the >>> synthetic case than what you patch does, which will also make _BQC >>> work. That can be discussed later though, the one-liner is simple, and >>> it works. >> >> So, let's assume that the one-liner goes into 3.11 and work further with that >> assumption. >> >> How would you address the sythetic case (on top of the one-liner)? > > I would write and read two values instead of one. The code is trying > to check if _BQC is always returning the maximum, and if you try with The code is introduced by commit a50188dae3089dcd15a6ae793528c157680891f1 where the broken system will always return a constant value for _BQC, either 0 or 100. So the commit at that time tries to not test a maximum value for the quirk. Then we have the ASUS NV56Z problem and its problem is explained in: https://github.com/aaronlu/linux/commit/0a3d2c5b59caf80ae5bb1ca1fda0f7bf448b38c9 And due to its reverse order of _BCL, testing the minimum value is not good either. So if the two values test is going to be adopted, I would suggest avoid testing edge values. But then I'm not sure if it is still worth to test two values instead of one. > two values you can be absolutely certain if that's happening or not; > it doesn't even matter which values you choose. Even in the synthetic > case that only has two values the check would work correctly and > detect that _BQC works correctly (or not). > > In my machine I think the issue is slightly different, I think _BCM is > failing, at least until enabling the _DOS thing, but at the end of the > day it's the same thing for the check; _BQC is always returning the > same value, and the code above will find that out, regardless of which > values are tested. If you think _BCM fails before _DOS and that makes acpi_video_bqc_quirk not correct, I think you can call acpi_video_bus_start_devices before the acpi_video_bus_get_devices in acpi_video_bus_add to make _BCM work before we do the quirk test and then add some debug prints in acpi_video_bqc_quirk and add some test levels to check it out. -Aaron > > For my particular machine though, I think it's more interesting to > find out why _BCM is failing before _DOS, and why efaa14c made it > work. If that is actually the case. -- 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
