[PATCH] drm/xe: Fix wa_oob codegen recipe for external module builds

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

When building with 'make M=drivers/gpu/drm/xe modules', kbuild invokes
scripts/Makefile.build with obj=., causing $(obj) to expand to '.'.
Make normalizes './xe_gen_wa_oob' to 'xe_gen_wa_oob' when constructing
the $^ automatic variable (target name normalization), so the recipe
command becomes just 'xe_gen_wa_oob ...' without any path prefix, and
the shell cannot find the tool.

Fix by replacing $^ with explicit $(obj)/xe_gen_wa_oob and
$(src)/<rules-file> references in both wa_oob recipe commands.
In recipe strings, make does not apply target name normalization, so
$(obj)/xe_gen_wa_oob correctly expands to './xe_gen_wa_oob' and the
shell can execute it. This matches the pattern already used by other
DRM drivers (e.g. radeon's mkregtable).

Fixes: f037e0b78e6d ("drm/xe: add xe_device_wa infrastructure")
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-xe@lists.freedesktop.org
Assisted-by: GitHub_Copilot:claude-sonnet-4.6
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 drivers/gpu/drm/xe/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index 09661f079d03..8e7b146880f4 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -16,14 +16,14 @@ subdir-ccflags-y += -I$(obj) -I$(src)
 hostprogs := xe_gen_wa_oob
 generated_oob := $(obj)/generated/xe_wa_oob.c $(obj)/generated/xe_wa_oob.h
 quiet_cmd_wa_oob = GEN     $(notdir $(generated_oob))
-      cmd_wa_oob = mkdir -p $(@D); $^ $(generated_oob)
+      cmd_wa_oob = mkdir -p $(@D); $(obj)/xe_gen_wa_oob $(src)/xe_wa_oob.rules $(generated_oob)
 $(obj)/generated/%_wa_oob.c $(obj)/generated/%_wa_oob.h: $(obj)/xe_gen_wa_oob \
 		 $(src)/xe_wa_oob.rules
 	$(call cmd,wa_oob)
 
 generated_device_oob := $(obj)/generated/xe_device_wa_oob.c $(obj)/generated/xe_device_wa_oob.h
 quiet_cmd_device_wa_oob = GEN	$(notdir $(generated_device_oob))
-      cmd_device_wa_oob = mkdir -p $(@D); $^ $(generated_device_oob)
+      cmd_device_wa_oob = mkdir -p $(@D); $(obj)/xe_gen_wa_oob $(src)/xe_device_wa_oob.rules $(generated_device_oob)
 $(obj)/generated/%_device_wa_oob.c $(obj)/generated/%_device_wa_oob.h: $(obj)/xe_gen_wa_oob \
 		 $(src)/xe_device_wa_oob.rules
 	$(call cmd,device_wa_oob)
-- 
2.54.0