Re: [PATCH 09/14] drm/xe: Abstract the initial FB PTE checks a bit

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, May 18, 2026 at 10:15:10AM +0200, Maarten Lankhorst wrote:
> Hey Ville,
> 
> Den 2026-05-11 kl. 23:41, skrev Ville Syrjala:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Add a few helpers that allow us to abstract the xe initial FB PTE
> > check a bit. Still very ad-hoc compared to the nicely abstracted
> > i915 counterpart, but whatever.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/xe/display/xe_initial_plane.c | 17 ++++++++++++++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/xe/display/xe_initial_plane.c b/drivers/gpu/drm/xe/display/xe_initial_plane.c
> > index b7e0685351bb..0dabc5709d01 100644
> > --- a/drivers/gpu/drm/xe/display/xe_initial_plane.c
> > +++ b/drivers/gpu/drm/xe/display/xe_initial_plane.c
> > @@ -18,8 +18,19 @@
> >  #include "xe_fb_pin.h"
> >  #include "xe_ggtt.h"
> >  #include "xe_mmio.h"
> > +#include "xe_ttm_stolen_mgr.h"
> >  #include "xe_vram_types.h"
> >  
> > +static bool is_pte_local(u64 pte)
> > +{
> > +	return pte & XE_GGTT_PTE_DM;
> > +}
> > +
> > +static bool need_pte_local(struct xe_device *xe)
> > +{
> > +	return IS_DGFX(xe);
> > +}
> > +
> >  static struct xe_bo *
> >  initial_plane_bo(struct xe_device *xe,
> >  		 struct intel_initial_plane_config *plane_config)
> > @@ -43,13 +54,13 @@ initial_plane_bo(struct xe_device *xe,
> >  	if (IS_DGFX(xe)) {
> >  		u64 pte = xe_ggtt_read_pte(tile0->mem.ggtt, base);
> >  
> > -		if (!(pte & XE_GGTT_PTE_DM)) {
> > -			drm_err(&xe->drm,
> > -				"Initial plane programming missing DM bit\n");
> > +		if (is_pte_local(pte) != need_pte_local(xe)) {
> > +			drm_err(&xe->drm, "Initial plane PTE has bad local memory bit\n");
> >  			return NULL;
> >  		}
> This is unnecessary, this is already inside the IS_DGFX branch, so all you're doing is checking twice.
> Remove need_pte_local and use the has_lmembar() check directly in the next patch?

The point is to abstract this mess to look a bit more like the clean
version in i915. Ideally I'd like to end up with a single codepath like
in i915, but xe doesn't seem to have anything like intel_mem_region
so it's a bit hard to achieve right now :(

> 
> >  		phys_base = pte & ~(page_size - 1);
> > +
> >  		flags |= XE_BO_FLAG_VRAM0;
> >  
> >  		/*
> Extra newline.
> 
> Kind regards,
> ~Maarten Lankhorst

-- 
Ville Syrjälä
Intel