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

[Chris Wilson]

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 at intel.com>
Reported-by: Leonard Crestez <leonard.crestez at nxp.com>
Fixes: 43dc7fe2b211 ("drm: Mark up accesses of vblank->enabled outside of its spinlock")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_irq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index aa23b9833588..dac1b2593cb1 100644
--- 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
-- 
2.11.0