configure: Expose no acceleration by default (--with-default-accel=none)

Why? I am not sure, but it seems equally as valid as allowing the switch
to uxa/glamor as default. The runtime equivalent is Option "AccelMethod".

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

6 files changed, 49 insertions, 8 deletions

diff --git a/configure.ac b/configure.ac
index 5c3dd20c..94959f7d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -646,7 +646,7 @@ fi
 
 AC_ARG_WITH(default-accel,
 	    AS_HELP_STRING([--with-default-accel],
-			   [Select the default acceleration method [default=sna if enabled, otherwise uxa]]),
+			   [Select the default acceleration method out of glamor, none, sna, or uxa  [default is sna if enabled, otherwise uxa]]),
 			   [accel="$withval"],
 			   [accel="auto"])
 if test "x$accel" = "xyes"; then
@@ -698,7 +698,11 @@ fi
 
 if test "x$have_accel" = "xnone"; then
 	if test "x$KMS" = "xyes"; then
-		AC_MSG_ERROR([Invalid default acceleration option])
+		if test "x$SNA" != "xno" -o "x$UXA" != "xno"; then
+			AC_DEFINE(DEFAULT_ACCEL_METHOD, NONE, [Default acceleration method])
+		else
+			AC_MSG_ERROR([Invalid default acceleration option])
+		fi
 	fi
 	accel="none"
 fi
@@ -865,6 +869,11 @@ test -e `pwd $0`/README && cat `pwd $0`/README
 
 accel_msg=""
 if test "x$SNA" != "xno"; then
+	if test "$accel" = "none"; then
+		accel_msg="$accel_msg *none"
+	else
+		accel_msg="$accel_msg none"
+	fi
 	if test "$accel" = "sna"; then
 		accel_msg="$accel_msg *sna"
 	else
@@ -872,6 +881,13 @@ if test "x$SNA" != "xno"; then
 	fi
 fi
 if test "x$UXA" != "xno"; then
+	if test "x$SNA" = "xno"; then
+		if test "$accel" = "none"; then
+			accel_msg="$accel_msg *none"
+		else
+			accel_msg="$accel_msg none"
+		fi
+	fi
 	if test "$accel" = "uxa"; then
 		accel_msg="$accel_msg *uxa"
 	else
diff --git a/src/intel_driver.h b/src/intel_driver.h
index 4f6a7641..7ce6b752 100644
--- a/src/intel_driver.h
+++ b/src/intel_driver.h
@@ -135,6 +135,11 @@ int intel_get_master(ScrnInfoPtr scrn);
 int intel_put_master(ScrnInfoPtr scrn);
 void intel_put_device(ScrnInfoPtr scrn);
 
+#define IS_DEFAULT_ACCEL_METHOD(x) ({ \
+	enum { SNA, UXA, GLAMOR, NONE } default_accel_method__ = DEFAULT_ACCEL_METHOD; \
+	default_accel_method__ == x; \
+})
+
 #define hosted() (0)
 
 #endif /* INTEL_DRIVER_H */
diff --git a/src/intel_module.c b/src/intel_module.c
index d6a0d3c5..95200d0c 100644
--- a/src/intel_module.c
+++ b/src/intel_module.c
@@ -489,7 +489,7 @@ _xf86findDriver(const char *ident, XF86ConfDevicePtr p)
 	return NULL;
 }
 
-static enum accel_method { SNA, UXA, GLAMOR } get_accel_method(void)
+static enum accel_method { NONE, SNA, UXA, GLAMOR } get_accel_method(void)
 {
 	enum accel_method accel_method = DEFAULT_ACCEL_METHOD;
 	XF86ConfDevicePtr dev;
@@ -503,7 +503,9 @@ static enum accel_method { SNA, UXA, GLAMOR } get_accel_method(void)
 
 		s = xf86FindOptionValue(dev->dev_option_lst, "AccelMethod");
 		if (s ) {
-			if (strcasecmp(s, "sna") == 0)
+			if (strcasecmp(s, "none") == 0)
+				accel_method = NONE;
+			else if (strcasecmp(s, "sna") == 0)
 				accel_method = SNA;
 			else if (strcasecmp(s, "uxa") == 0)
 				accel_method = UXA;
@@ -562,9 +564,14 @@ intel_scrn_create(DriverPtr		driver,
 #if KMS
 	switch (get_accel_method()) {
 #if USE_SNA
-	case SNA: return sna_init_scrn(scrn, entity_num);
+	case NONE:
+	case SNA:
+		return sna_init_scrn(scrn, entity_num);
 #endif
 #if USE_UXA
+#if !USE_SNA
+	case NONE:
+#endif
 	case GLAMOR:
 	case UXA:
 		  return intel_init_scrn(scrn);
diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
index e4d6f82f..00ff492a 100644
--- a/src/sna/sna_accel.c
+++ b/src/sna/sna_accel.c
@@ -17625,7 +17625,7 @@ static bool sna_option_accel_none(struct sna *sna)
 
 	s = xf86GetOptValString(sna->Options, OPTION_ACCEL_METHOD);
 	if (s == NULL)
-		return false;
+		return IS_DEFAULT_ACCEL_METHOD(NONE);
 
 	return strcasecmp(s, "none") == 0;
 }
diff --git a/src/uxa/intel_glamor.c b/src/uxa/intel_glamor.c
index 0be87b80..9d2792f9 100644
--- a/src/uxa/intel_glamor.c
+++ b/src/uxa/intel_glamor.c
@@ -87,12 +87,11 @@ intel_glamor_create_screen_resources(ScreenPtr screen)
 static Bool
 intel_glamor_enabled(intel_screen_private *intel)
 {
-	enum { SNA, UXA, GLAMOR } default_accel_method = DEFAULT_ACCEL_METHOD;
 	const char *s;
 
 	s = xf86GetOptValString(intel->Options, OPTION_ACCEL_METHOD);
 	if (s == NULL)
-		return default_accel_method == GLAMOR;
+		return IS_DEFAULT_ACCEL_METHOD(GLAMOR);
 
 	return strcasecmp(s, "glamor") == 0;
 }
diff --git a/src/uxa/intel_uxa.c b/src/uxa/intel_uxa.c
index b3961881..255a245f 100644
--- a/src/uxa/intel_uxa.c
+++ b/src/uxa/intel_uxa.c
@@ -1421,6 +1421,17 @@ intel_limits_init(intel_screen_private *intel)
 	}
 }
 
+static Bool intel_option_accel_none(intel_screen_private *intel)
+{
+	const char *s;
+
+	s = xf86GetOptValString(intel->Options, OPTION_ACCEL_METHOD);
+	if (s == NULL)
+		return IS_DEFAULT_ACCEL_METHOD(NONE);
+
+	return strcasecmp(s, "none") == 0;
+}
+
 static Bool intel_option_accel_blt(intel_screen_private *intel)
 {
 	const char *s;
@@ -1542,6 +1553,9 @@ Bool intel_uxa_init(ScreenPtr screen)
 		return FALSE;
 	}
 
+	if (intel_option_accel_none(intel))
+		intel->force_fallback = true;
+
 	uxa_set_fallback_debug(screen, intel->fallback_debug);
 	uxa_set_force_fallback(screen, intel->force_fallback);