drm/msm/gen_header: allow skipping the validation

We don't need to run the validation of the XML files if we are just
compiling the kernel. Skip the validation unless the user enables
corresponding Kconfig option. This removes a warning from gen_header.py
about lxml being not installed.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/all/20240409120108.2303d0bd@canb.auug.org.au/Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/592558/Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/Kconfig

@@ -54,6 +54,14 @@ config DRM_MSM_GPU_SUDO
 	  Only use this if you are a driver developer.  This should *not*
 	  be enabled for production kernels.  If unsure, say N.
 
+config DRM_MSM_VALIDATE_XML
+	bool "Validate XML register files against schema"
+	depends on DRM_MSM && EXPERT
+	depends on $(success,$(PYTHON3) -c "import lxml")
+	help
+	  Validate XML files with register definitions against rules-fd schema.
+	  This option is mostly targeting DRM MSM developers. If unsure, say N.
+
 config DRM_MSM_MDSS
 	bool
 	depends on DRM_MSM

drivers/gpu/drm/msm/Makefile

@@ -156,8 +156,15 @@ msm-y += $(adreno-y) $(msm-display-y)
 
 obj-$(CONFIG_DRM_MSM)	+= msm.o
 
+ifeq (y,$(CONFIG_DRM_MSM_VALIDATE_XML))
+	headergen-opts += --validate
+else
+	headergen-opts += --no-validate
+endif
+
 quiet_cmd_headergen = GENHDR  $@
-      cmd_headergen = mkdir -p $(obj)/generated && $(PYTHON3) $(srctree)/$(src)/registers/gen_header.py --rnn $(srctree)/$(src)/registers --xml $< c-defines > $@
+      cmd_headergen = mkdir -p $(obj)/generated && $(PYTHON3) $(srctree)/$(src)/registers/gen_header.py \
+		      $(headergen-opts) --rnn $(srctree)/$(src)/registers --xml $< c-defines > $@
 
 $(obj)/generated/%.xml.h: $(src)/registers/adreno/%.xml \
 		$(src)/registers/adreno/adreno_common.xml \

drivers/gpu/drm/msm/registers/gen_header.py

@@ -538,6 +538,9 @@ class Parser(object):
 		self.variants.add(reg.domain)
 
 	def do_validate(self, schemafile):
+		if self.validate == False:
+			return
+
 		try:
 			from lxml import etree
 
@@ -567,7 +570,10 @@ class Parser(object):
 			if not xmlschema.validate(xml_doc):
 				error_str = str(xmlschema.error_log.filter_from_errors()[0])
 				raise self.error("Schema validation failed for: " + filename + "\n" + error_str)
-		except ImportError:
+		except ImportError as e:
+			if self.validate:
+				raise e
+
 			print("lxml not found, skipping validation", file=sys.stderr)
 
 	def do_parse(self, filename):
@@ -586,9 +592,10 @@ class Parser(object):
 		self.stack.pop()
 		file.close()
 
-	def parse(self, rnn_path, filename):
+	def parse(self, rnn_path, filename, validate):
 		self.path = rnn_path
 		self.stack = []
+		self.validate = validate
 		self.do_parse(filename)
 
 	def parse_reg(self, attrs, bit_size):
@@ -853,7 +860,7 @@ def dump_c(args, guard, func):
 	p = Parser()
 
 	try:
-		p.parse(args.rnn, args.xml)
+		p.parse(args.rnn, args.xml, args.validate)
 	except Error as e:
 		print(e, file=sys.stderr)
 		exit(1)
@@ -941,6 +948,7 @@ def main():
 	parser = argparse.ArgumentParser()
 	parser.add_argument('--rnn', type=str, required=True)
 	parser.add_argument('--xml', type=str, required=True)
+	parser.add_argument('--validate', action=argparse.BooleanOptionalAction)
 
 	subparsers = parser.add_subparsers()
 	subparsers.required = True