On Mon, Oct 07, 2013 at 10:15:16AM +0100, Chris Wilson wrote: > On Wed, Oct 02, 2013 at 04:42:55PM +0300, ville.syrjala@xxxxxxxxxxxxxxx wrote: > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > We have several problems with out VGA handling: > > - We try to use the GMCH control VGA disable bit even though it may > > be locked > > - If we manage to disable VGA throuh GMCH control, we're no longer > > able to correctly disable the VGA plane > > - Taking part in the VGA arbitration is too expensive for X [1] > > > > So let's treat the GMCH control VGA disable bit as read-only and leave > > it for the BIOS to set, as it was intended. To disable VGA we will use > > the VGA misc register, and to disable VGA IO we will disable IO space > > completely via the PCI command register. > > > > But we still need VGA register access during resume (and possibly during > > lid event on insane BIOSen) to disable the VGA plane. Also we need to > > re-disable VGA memory decode via the VGA misc register on resume. > > > > Luckily up to gen4, VGA registers can be accessed through MMIO. > > Unfortunately from gen5 onwards only the legacy VGA IO port range > > works. So on gen5+ we still need IO space to be enabled during those > > few special moments when we need to access VGA registers. > > > > We still want to opt out of VGA arbitration on gen5+, so we have keep > > IO space disabled most of the time. And when we do need to poke at VGA > > registers, we enable IO space briefly while no one is looking. To > > guarantee that no one is looking we will use stop_machine(). > > > > [1] http://lists.x.org/archives/xorg-devel/2013-September/037763.html > > > > v2: Use SNB_GMCH_TRL on SNB+ > > Use port IO instead of MMIO on CTG/ELK > > Add WaEnableVGAAccessThroughIOPort comment > > Fix the max number of devices on the bus limit > > v3: Allocate the temp space dynamically > > Print some errors if we fail to execute the vga "op" due to alloc failure > > Passes the dGPU test, the SNB laptop, but is doa for CTG. Crap. And v2 still works all right there? -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
