check presence of drmSetClientCap()

Old libdrm doesn't have drmSetClientCap() and libhost1x fails to compile
in this case. The drmSetClientCap() is optional and needed only by modern
kernels, hence we could compile it conditionally.

configure.ac

@@ -66,6 +66,16 @@ AC_CHECK_HEADER([envytools/rnn.h],
 	[AC_CHECK_LIB([rnn], [rnn_init], [enable_rnn=yes], [enable_rnn=no], [-lenvyutil -lxml2])])
 AM_CONDITIONAL([ENABLE_RNN], [test "x$enable_rnn" = "xyes"])
 
+SAVE_CPPFLAGS="$CPPFLAGS"
+CPPFLAGS="$CPPFLAGS $DRM_CFLAGS"
+
+AC_CHECK_DECL(drmSetClientCap,
+	      [AC_DEFINE(HAVE_LIBDRM_CLIENT_CAP, 1,
+	      [Have drmSetClientCap API])], [],
+	      [#include <xf86drm.h>])
+
+CPPFLAGS="$SAVE_CPPFLAGS"
+
 AC_CONFIG_FILES([
 	src/libgrate/libgrate.pc
 ])

src/libhost1x/host1x-drm.c

@@ -21,6 +21,10 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
 #include <errno.h>
 #include <fcntl.h>
 #include <stdbool.h>
@@ -550,6 +554,7 @@ static int drm_display_create(struct drm_display **displayp, struct drm *drm)
 	if (err < 0)
 		goto try_x11;
 
+#ifdef HAVE_LIBDRM_CLIENT_CAP
 	err = drmSetClientCap(drm->fd, DRM_CLIENT_CAP_ATOMIC, 1);
 	if (err)
 		host1x_error("drmSetClientCap(ATOMIC) failed: %d\n", err);
@@ -558,6 +563,7 @@ static int drm_display_create(struct drm_display **displayp, struct drm *drm)
 	if (err)
 		host1x_error("drmSetClientCap(UNIVERSAL_PLANES) failed: %d\n",
 			     err);
+#endif
 
 	err = drm_display_setup(display, drm->base.options->display_id);
 	if (err < 0)

src/libhost1x/meson.build

@@ -38,6 +38,14 @@ if x11.found() and \
 	libhost1x_deps += dependency('xcb-icccm')
 endif
 
+cc = meson.get_compiler('c')
+
+if cc.has_function('drmSetClientCap',
+                   prefix: '#include <xf86drm.h>',
+                   dependencies : [libdrm])
+	libhost1x_c_args += '-DHAVE_LIBDRM_CLIENT_CAP'
+endif
+
 libhost1x = shared_library('host1x',
 	libhost1x_sources,
 	include_directories : include_directories('../../include'),