HQVDP_MBX_SOFT_VSYNC
writel(SOFT_VSYNC_HW, hqvdp->regs + HQVDP_MBX_SOFT_VSYNC);
DBGFS_DUMP(HQVDP_MBX_SOFT_VSYNC);
if (!(readl(hqvdp->regs + HQVDP_MBX_SOFT_VSYNC) & 3))
writel(SOFT_VSYNC_SW_CTRL_IRQ, hqvdp->regs + HQVDP_MBX_SOFT_VSYNC);