drm: Convert cmpxchg(bool) back to a two step operation

ARM v6 (at least) only allows cmpxchg on 32bit variables which doesn't
always include the bool type.

drivers/built-in.o: In function `vblank_disable_and_save':
imx-ocotp.c:(.text+0xb45e8): undefined reference to `__bad_cmpxchg'
Makefile:986: recipe for target 'vmlinux' failed

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reported-by: Leonard Crestez <leonard.crestez@nxp.com>
Fixes: 43dc7fe2b211 ("drm: Mark up accesses of vblank->enabled outside of its spinlock")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170330140832.32377-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index aa23b9833588843bc0a1d96448ddcaf5937ca35b..dac1b2593cb15324372164ab70f2855e67cb5979 100644 (file)
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -338,8 +338,10 @@ static void vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
         * calling the ->disable_vblank() operation in atomic context with the
         * hardware potentially runtime suspended.
         */
-       if (cmpxchg_relaxed(&vblank->enabled, true, false))
+       if (vblank->enabled) {
                __disable_vblank(dev, pipe);
+               vblank->enabled = false;
+       }
 
        /*
         * Always update the count and timestamp to maintain the