On Fri, 4 Jun 2021 at 15:08, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > On Fri, Jun 04, 2021 at 02:47:16PM +0100, Emil Velikov wrote: > > On Wed, 26 May 2021 at 17:21, Emil Velikov <emil.l.velikov@xxxxxxxxx> wrote: > > > > > > Hi Ville, > > > > > > On Tue, 18 May 2021 at 12:17, Ville Syrjälä > > > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > > On Tue, May 18, 2021 at 12:09:56PM +0100, Emil Velikov wrote: > > > > > Hi Ville, > > > > > > > > > > On Mon, 17 May 2021 at 18:24, Ville Syrjälä > > > > > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > On Sun, May 16, 2021 at 06:14:32PM +0100, Emil Velikov wrote: > > > > > > > From: Vivek Das Mohapatra <vivek@xxxxxxxxxxxxx> > > > > > > > > > > > > > > This patch is to do with seamless handover, eg when the sequence is > > > > > > > bootloader → plymouth → desktop. > > > > > > > > > > > > > > It switches the vga arbiter from the "other" GPU to the default one > > > > > > > (intel in this case), so the driver can issue some io(). > > > > > > > > > > > > I don't understand what this commit message is trying to say. > > > > > > > > > > > Bunch of context is lost due to the patch age, so I'm not 100% sure of > > > > > the actual hardware setup where this occurs. > > > > > Does the following make sense? > > > > > > > > > > Currently on dual GPU systems, we do not get seamless handover as the > > > > > output flickers during the transition bootloader -> plymouth -> > > > > > desktop. > > > > > This happens as a result of switching (via the VGA arbiter) from the > > > > > "other" GPU back to the default i915 one and issuing io() commands. > > > > > > > > Hmm. Does this work? > > > > > > > > --- a/drivers/gpu/drm/i915/display/intel_vga.c > > > > +++ b/drivers/gpu/drm/i915/display/intel_vga.c > > > > @@ -29,6 +29,9 @@ void intel_vga_disable(struct drm_i915_private *dev_priv) > > > > i915_reg_t vga_reg = intel_vga_cntrl_reg(dev_priv); > > > > u8 sr1; > > > > > > > > + if (intel_de_read(dev_priv, vga_reg) & VGA_DISP_DISABLE) > > > > + return; > > > > + > > > > /* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */ > > > > vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO); > > > > outb(SR01, VGA_SR_INDEX); > > > > > > > Was able to replicate the issue somewhat and the above does help quite a lot. > > > Feel free to add my: > > > Reviewed-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> > > > Tested-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> > > > > > Humble poke. > > > > Cannot see this patch in the drm-misc or drm-intel trees. Is there > > anything I do to help move it forward? > > Can you just respin the patch with this? > I've used your suggestion and redone the commit message completely. Hope it's far less cryptic now. Patch is on the ML - realised I didn't CC you, just as it went out. https://lore.kernel.org/dri-devel/20210604154905.660142-1-emil.l.velikov@xxxxxxxxx/T/#u Thanks -Emil
