On Wed, Mar 11, 2015 at 10:34:45PM +0100, Bruno Prémont wrote: > As GMUX depends on IO for iGP to be enabled and active, lock the IO at > vgaarb level. This should prevent GPU driver for dGPU to disable IO for > iGP while it tries to own legacy VGA IO. > > This fixes usage of backlight control combined with closed nvidia > driver on some Apple dual-GPU (intel/nvidia) systems. > > On those systems loading nvidia driver disables intel IO decoding, > disabling the gmux backlight controls as a side effect. > Prior to commits moving boot_vga from (optional) efifb to less optional > vgaarb this mis-behavior could be avoided by using right kernel config > (efifb enabled but vgaarb disabled). > > This patch explicitly does not try to trigger vgaarb changes in order > to avoid confusing already running graphics drivers. If IO has been > mis-configured by vgaarb gmux will thus fail to probe. > It is expected to load/probe gmux prior to graphics drivers. > > Fixes: ce027dac592c0ada241ce0f95ae65856828ac450 # nvidia interaction > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=86121 > Reported-by: Petri Hodju <petrihodju@xxxxxxxxx> > Tested-by: Petri Hodju <petrihodju@xxxxxxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: Matthew Garrett <matthew.garrett@xxxxxxxxxx> > Signed-off-by: Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx> > --- > Resending v2 in the hope Darren won't hit quoted-printable. > Also adding linux-pci on CC by Bjorn's request in bugzilla. Much better, thanks. Queued. -- Darren Hart Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
