Completely disable 2D acceleration on Broadwell

[Mark Kettenis]

As tedu@ reported (and some pople on misc@ confirmed) partly disabling
2D acceleration on Broadwell made X unstable.  It really looks like
the alternative BLT path isn't well tested and therefore buggy.  So
here is a diff that disables 2D acceleration completely.  Those who
don't care about suspend/resume can still enable it if they want.  3D
acceleration should continue to work.

ok?


Index: sna_accel.c
===================================================================
RCS file: /home/cvs/xenocara/driver/xf86-video-intel/src/sna/sna_accel.c,v
retrieving revision 1.6
diff -u -p -r1.6 sna_accel.c
--- sna_accel.c 15 Nov 2015 15:33:57 -0000      1.6
+++ sna_accel.c 1 Dec 2015 15:37:44 -0000
@@ -17659,6 +17659,9 @@ static bool sna_option_accel_none(struct
                return true;
 
        s = xf86GetOptValString(sna->Options, OPTION_ACCEL_METHOD);
+       /* XXX avoid render ring since it gets stuck after resume */
+       if (s == NULL && sna->info->gen >= 0100)
+               return true;
        if (s == NULL)
                return IS_DEFAULT_ACCEL_METHOD(NOACCEL);
 
@@ -17670,9 +17673,6 @@ static bool sna_option_accel_blt(struct 
        const char *s;
 
        s = xf86GetOptValString(sna->Options, OPTION_ACCEL_METHOD);
-       /* XXX avoid render ring since it gets stuck after resume */
-       if (s == NULL && sna->info->gen >= 0100)
-               return true;
        if (s == NULL)
                return false;