drm/rockchip: Do not use memcpy for MMIO addresses

memcpy is only meant to be used for memory, and only that.
MMIO accessors should be used to access MMIO regions, preferably
the ones that correspond to the size of the register accessed.

Let's convert the bulk register copy to writel/readl_relaxed,
which is the correct API.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20180220130120.5254-3-marc.zyngier@arm.com

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -519,7 +519,10 @@ static int vop_enable(struct drm_crtc *crtc)
 		goto err_disable_aclk;
 	}
 
-	memcpy(vop->regs, vop->regsbak, vop->len);
+	spin_lock(&vop->reg_lock);
+	for (i = 0; i < vop->len; i += 4)
+		writel_relaxed(vop->regsbak[i / 4], vop->regs + i);
+
 	/*
 	 * We need to make sure that all windows are disabled before we
 	 * enable the crtc. Otherwise we might try to scan from a destroyed
@@ -529,10 +532,9 @@ static int vop_enable(struct drm_crtc *crtc)
 		struct vop_win *vop_win = &vop->win[i];
 		const struct vop_win_data *win = vop_win->data;
 
-		spin_lock(&vop->reg_lock);
 		VOP_WIN_SET(vop, win, enable, 0);
-		spin_unlock(&vop->reg_lock);
 	}
+	spin_unlock(&vop->reg_lock);
 
 	vop_cfg_done(vop);
 
@@ -1404,7 +1406,8 @@ static int vop_initial(struct vop *vop)
 	VOP_INTR_SET_TYPE(vop, clear, INTR_MASK, 1);
 	VOP_INTR_SET_TYPE(vop, enable, INTR_MASK, 0);
 
-	memcpy(vop->regsbak, vop->regs, vop->len);
+	for (i = 0; i < vop->len; i += sizeof(u32))
+		vop->regsbak[i / 4] = readl_relaxed(vop->regs + i);
 
 	VOP_REG_SET(vop, misc, global_regdone_en, 1);
 	VOP_REG_SET(vop, common, dsp_blank, 0);