The vertical back porch field in ATMEL_HLCDC_CFG(2) was programmed
without subtracting 1, unlike the other timing parameters which follow
the controller???s (value - 1) encoding requirement.
This results in an off-by-one error in the vertical back porch timing.

Signed-off-by: Manikandan Muralidharan <[email protected]>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c 
b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 9dbac2def333..7932d666e9ec 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -115,7 +115,7 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc 
*c)
                     (vm.hsync_len - 1) | ((vm.vsync_len - 1) << 16));
 
        regmap_write(regmap, ATMEL_HLCDC_CFG(2),
-                    (vm.vfront_porch - 1) | (vm.vback_porch << 16));
+                    (vm.vfront_porch - 1) | ((vm.vback_porch - 1) << 16));
 
        regmap_write(regmap, ATMEL_HLCDC_CFG(3),
                     (vm.hfront_porch - 1) | ((vm.hback_porch - 1) << 16));
-- 
2.25.1

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