Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 2ca77ad..e145e4d 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -2,7 +2,12 @@
 # Makefile for Sphinx documentation
 #
 
-subdir-y :=
+subdir-y := devicetree/bindings/
+
+# Check for broken documentation file references
+ifeq ($(CONFIG_WARN_MISSING_DOCUMENTS),y)
+$(shell $(srctree)/scripts/documentation-file-ref-check --warn)
+endif
 
 # You can set these variables from the command line.
 SPHINXBUILD   = sphinx-build
@@ -23,13 +28,20 @@
 .DEFAULT:
 	$(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.)
 	@echo
-	@./scripts/sphinx-pre-install
+	@$(srctree)/scripts/sphinx-pre-install
 	@echo "  SKIP    Sphinx $@ target."
 
 else # HAVE_SPHINX
 
-# User-friendly check for pdflatex
+export SPHINXOPTS = $(shell perl -e 'open IN,"sphinx-build --version 2>&1 |"; while (<IN>) { if (m/([\d\.]+)/) { print "-jauto" if ($$1 >= "1.7") } ;} close IN')
+
+# User-friendly check for pdflatex and latexmk
 HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi)
+HAVE_LATEXMK := $(shell if which latexmk >/dev/null 2>&1; then echo 1; else echo 0; fi)
+
+ifeq ($(HAVE_LATEXMK),1)
+	PDFLATEX := latexmk -$(PDFLATEX)
+endif #HAVE_LATEXMK
 
 # Internal variables.
 PAPEROPT_a4     = -D latex_paper_size=a4
@@ -65,12 +77,14 @@
 	$(abspath $(BUILDDIR)/$3/$4)
 
 htmldocs:
+	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))
 
 linkcheckdocs:
 	@$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var)))
 
 latexdocs:
+	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var)))
 
 ifeq ($(HAVE_PDFLATEX),0)
@@ -82,14 +96,17 @@
 else # HAVE_PDFLATEX
 
 pdfdocs: latexdocs
-	$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX=$(PDFLATEX) LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;)
+	@$(srctree)/scripts/sphinx-pre-install --version-check
+	$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX="$(PDFLATEX)" LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;)
 
 endif # HAVE_PDFLATEX
 
 epubdocs:
+	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var)))
 
 xmldocs:
+	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var)))
 
 endif # HAVE_SPHINX