Date: Mon, 25 Feb 2013 13:30:56 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-acpi@freebsd.org Cc: freebsd-current@freebsd.org Subject: Re: Fixing X220 Video The Right Way Message-ID: <201302251330.57034.jhb@freebsd.org> In-Reply-To: <512A6FFF.2060603@gmail.com> References: <512A6FFF.2060603@gmail.com>
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On Sunday, February 24, 2013 2:54:39 pm matt wrote: > I am working on fixing acpi_video for X220. > > My X220 is back to FreeBSD land, and I always felt \VBRC calls were dirty. > So I've set out to fix acpi_video to work naturally, as it does in linux > land. > > Background: > Lenovo laptops boot in a mode where the brightness keys automagically > work, under BIOS/EC control. > This gets blown away (for us) shortly after Kernel attach. > > At this point, the acpi method \NBCF will return 0, which means acpi > cannot control video brightness. > > Once we touch the _BCL method on the video output (even inactive ones), > \NBCF returns 1 and will allow acpi control. > > You may remember that acpi_video records some brightness value that > changes with keypresses, but does not work on X220. > > Current status: > If I modify acpi video to attach to \_SB.PCI0.PEG.VID, brightness works > via sysctl but not keypress (\NBCF = 1) > > If I leave that alone, but just redirect the brightness set function to > \_SB.PCI0.PEG.VID.LCD0._BCM, the keyboard works > > That is obviously a hack, but it indicates something is going on here. > > I think that get_acpi_handle() on the X220 vgapci is returning the wrong > ACPI_HANDLE. > Perhaps this is why the screen stays off when resume used to work? > > Obviously it can be fixed by hard coding this path into acpi_video, but > I feel like that is definitely the wrong way. > A tunable for an acpi_video override might be useful, but it still > leaves potentially the wrong path in vgapci's IVARs. > > Is there a better place to "correct" the ACPI_PATH that gets stored in > vgapci's ivar? Is there already a tunable I can use to fix this? vgapci's ivar is set by the PCI address. Do you have multiple vgapci devices? -- John Baldwin
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