diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index 4332da48b1b3..1b6c2253192e 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -62,7 +62,7 @@ static unsigned long sun4i_dclk_recalc_rate(struct clk_hw *hw,
 	regmap_read(dclk->regmap, SUN4I_TCON0_DCLK_REG, &val);
 
 	val >>= SUN4I_TCON0_DCLK_DIV_SHIFT;
-	val &= SUN4I_TCON0_DCLK_DIV_WIDTH;
+	val &= (1 << SUN4I_TCON0_DCLK_DIV_WIDTH) - 1;
 
 	if (!val)
 		val = 1;