On Thu, 2020-11-26 at 16:43 +0000, Robin Murphy wrote: > On 2020-11-11 12:38, Yong Wu wrote: > > In attach device, it will update the pagetable base address register. > > Move the hw_init function also here. Then it only need call > > pm_runtime_get/put one time here if m4u has power domain. > > Doesn't that mean you'll end up writing most of the registers twice > every time? (first from mtk_iommu_resume(), then again from > mtk_iommu_hw_init()) I have skipped the first resume from mtk_iommu_resume with the code in [15/24]: @@ -828,6 +848,9 @@ static int __maybe_unused mtk_iommu_runtime_resume(struct device *dev) +/* Avoid first resume to affect the default value of registers below.*/ +if (!m4u_dom) + return 0; > It might be neater to have mtk_iommu_hw_init() simply populate the > mtk_iommu_suspend_reg data with the initial values at probe time and > manually call mtk_iommu_resume() if the hardware is already powered up > at that point. Or maybe just don't bother saving those registers on Yes. All the power-domains are enabled in lk when bootup. Actually I have plan to remove the pm_runtime_get in this attach_device in the later patchset. This is for fixing a issue that the screen is turned off when bootup. In android project. we always show boot image. If iommu call pm_runtime_get/put here, the display power-domain will be turned off here given that iommu always probe before display drivers and iommu's power-domain always is display's power-domain. Even I plan to move the device's pm_runtime_enable into this attach_device in the case all the drivers(iommu and display...) build as modules. it is for skipping turn off display's power-domain in genpd_power_off_unused. This is only a plan, I'm not sure if power-domain could fix it like[1]. In this patchset, I'd like to keep current status. [1] https://patchwork.kernel.org/project/linux-clk/patch/20190630150230.7878-3-robdclark@xxxxxxxxx/ > suspend and put the initialisation directly in the resume path. > > Robin. > > > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx> > > --- > > drivers/iommu/mtk_iommu.c | 10 ++++++---- > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > > index 55f9b329e637..cfdf5ce696fd 100644 > > --- a/drivers/iommu/mtk_iommu.c > > +++ b/drivers/iommu/mtk_iommu.c > > @@ -125,6 +125,8 @@ struct mtk_iommu_domain { > > > > static const struct iommu_ops mtk_iommu_ops; > > > > +static int mtk_iommu_hw_init(const struct mtk_iommu_data *data); > > + > > /* > > * In M4U 4GB mode, the physical address is remapped as below: > > * > > @@ -380,12 +382,16 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain, > > { > > struct mtk_iommu_data *data = dev_iommu_priv_get(dev); > > struct mtk_iommu_domain *dom = to_mtk_domain(domain); > > + int ret; > > > > if (!data) > > return -ENODEV; > > > > /* Update the pgtable base address register of the M4U HW */ > > if (!data->m4u_dom) { > > + ret = mtk_iommu_hw_init(data); > > + if (ret) > > + return ret; > > data->m4u_dom = dom; > > writel(dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK, > > data->base + REG_MMU_PT_BASE_ADDR); > > @@ -729,10 +735,6 @@ static int mtk_iommu_probe(struct platform_device *pdev) > > > > platform_set_drvdata(pdev, data); > > > > - ret = mtk_iommu_hw_init(data); > > - if (ret) > > - return ret; > > - > > ret = iommu_device_sysfs_add(&data->iommu, dev, NULL, > > "mtk-iommu.%pa", &ioaddr); > > if (ret) > >
