On 29/06/2020 09:13, Chao Hao wrote: > MT8173 is different from other SoCs for MMU_CTRL register. > For mt8173, its bit9 is in_order_write_en and doesn't use its > default 1'b1.> For other SoCs, bit[12] represents victim_tlb_en feature and > victim_tlb is enable defaultly(bit[12]=1), if we use > "regval = F_MMU_TF_PROT_TO_PROGRAM_ADDR", victim_tlb will be > disabled, it will drop iommu performace. > So we need to deal with the setting of MMU_CTRL separately > for mt8173 and others. > My proposal to rewrite the commit message: The MMU_CTRL regiser of MT8173 is different from other SoCs. The in_order_wr_en is bit[9] which is zero by default. Other SoCs have the vitcim_tlb_en feature mapped to bit[12]. This bit is set to one by default. We need to preserve the bit when setting F_MMU_TF_PROT_TO_PROGRAM_ADDR as otherwise the bit will be cleared and IOMMU performance will drop. > Suggested-by: Matthias Brugger <matthias.bgg@xxxxxxxxx> > Suggested-by: Yong Wu <yong.wu@xxxxxxxxxxxx> > Signed-off-by: Chao Hao <chao.hao@xxxxxxxxxxxx> > --- > drivers/iommu/mtk_iommu.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > index 8299a3299090..e46e2deee3fd 100644 > --- a/drivers/iommu/mtk_iommu.c > +++ b/drivers/iommu/mtk_iommu.c > @@ -543,11 +543,12 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data) > return ret; > } > > + regval = readl_relaxed(data->base + REG_MMU_CTRL_REG); The read is only needed in the else branch. > if (data->plat_data->m4u_plat == M4U_MT8173) > regval = F_MMU_PREFETCH_RT_REPLACE_MOD | > F_MMU_TF_PROT_TO_PROGRAM_ADDR_MT8173; > else > - regval = F_MMU_TF_PROT_TO_PROGRAM_ADDR; > + regval |= F_MMU_TF_PROT_TO_PROGRAM_ADDR; > writel_relaxed(regval, data->base + REG_MMU_CTRL_REG); > > regval = F_L2_MULIT_HIT_EN | >
