On Thu, Jul 11, 2013 at 01:35:40PM +0200, Daniel Vetter wrote: > It's in the PFIT_CONTROL register, but very much associated with the > lvds encoder. So move the readout for it (in the case of an otherwise > disabled pfit) from the pipe to the lvds encoder's get_config > function. > > Otherwise we get a pipe state mismatch if we use pipe B for a non-lvds > output and we've left the dither bit enabled behind us. This can > happen if the BIOS has set the bit (some seem to unconditionally do > that, even in the complete absence of an lvds port), but not enabled > pipe B at boot-up. Then we won't clear the pfit control register since > we can only touch that if the pfit is associated with our pipe in the > crtc configuration - we could trample over the pfit state of the other > pipe otherwise since it's shared. Once pipe B is enabled we notice > that the 6to8 dither bit is set and complain about the mismatch. > > Note that testing indicates that we don't actually need to set this > bit when the pfit is disabled, dithering on 18bpp panels seems to work > regardless. But ripping that code out is not something for a bugfix > meant for -rc kernels. > > v2: While at it clarify the logic in i9xx_get_pfit_config, spurred by > comments from Chris on irc. > > v3: Use Chris suggestion to make the control flow in > i9xx_get_pfit_config easier to understand. > > v4: Kill the extra line, spotted by Chris. > > Reported-by: Knut Petersen <Knut_Petersen at t-online.de> > Cc: Knut Petersen <Knut_Petersen at t-online.de> > Cc: Chris Wilson <chris at chris-wilson.co.uk> > References: http://lists.freedesktop.org/archives/intel-gfx/2013-July/030092.html > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk> -Chris -- Chris Wilson, Intel Open Source Technology Centre
