RISCV_IOMMU_DC_TC_V
if (!(tc & RISCV_IOMMU_DC_TC_V))
WRITE_ONCE(dc->tc, tc & ~RISCV_IOMMU_DC_TC_V);
tc |= ta & RISCV_IOMMU_DC_TC_V;
if (READ_ONCE(dc->tc) & RISCV_IOMMU_DC_TC_V)