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    SubjectRe: [PATCH v4 13/24] iommu/mediatek: Add device link for smi-common and m4u
    On Wed, Nov 11, 2020 at 8:40 PM Yong Wu <yong.wu@mediatek.com> wrote:
    >
    > In the lastest SoC, M4U has its special power domain. thus, If the engine
    > begin to work, it should help enable the power for M4U firstly.
    > Currently if the engine work, it always enable the power/clocks for
    > smi-larbs/smi-common. This patch adds device_link for smi-common and M4U.
    > then, if smi-common power is enabled, the M4U power also is powered on
    > automatically.
    >
    > Normally M4U connect with several smi-larbs and their smi-common always
    > are the same, In this patch it get smi-common dev from the first smi-larb
    > device(i==0), then add the device_link only while m4u has power-domain.
    >
    > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
    > ---
    > drivers/iommu/mtk_iommu.c | 36 +++++++++++++++++++++++++++++++++---
    > drivers/iommu/mtk_iommu.h | 1 +
    > 2 files changed, 34 insertions(+), 3 deletions(-)
    >
    > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
    > index cfdf5ce696fd..4ce7e0883e4d 100644
    > --- a/drivers/iommu/mtk_iommu.c
    > +++ b/drivers/iommu/mtk_iommu.c
    > @@ -20,6 +20,7 @@
    > #include <linux/of_irq.h>
    > #include <linux/of_platform.h>
    > #include <linux/platform_device.h>
    > +#include <linux/pm_runtime.h>
    > #include <linux/regmap.h>
    > #include <linux/slab.h>
    > #include <linux/spinlock.h>
    > @@ -705,7 +706,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
    > return larb_nr;
    >
    > for (i = 0; i < larb_nr; i++) {
    > - struct device_node *larbnode;
    > + struct device_node *larbnode, *smicomm_node;
    > struct platform_device *plarbdev;
    > u32 id;
    >
    > @@ -731,6 +732,26 @@ static int mtk_iommu_probe(struct platform_device *pdev)
    >
    > component_match_add_release(dev, &match, release_of,
    > compare_of, larbnode);
    > + if (!i) {

    Maybe more of a style preference, but since you are actually comparing
    an integer, I prefer seeing i == 0.

    Also, might be nicer to do

    if (i != 0)
    continue;

    And de-indent the rest.

    > + smicomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
    > + if (!smicomm_node)
    > + return -EINVAL;
    > +
    > + plarbdev = of_find_device_by_node(smicomm_node);
    > + of_node_put(smicomm_node);
    > + data->smicomm_dev = &plarbdev->dev;
    > + }
    > + }
    > +
    > + if (dev->pm_domain) {
    > + struct device_link *link;
    > +
    > + link = device_link_add(data->smicomm_dev, dev,
    > + DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
    > + if (!link) {
    > + dev_err(dev, "Unable link %s.\n", dev_name(data->smicomm_dev));
    > + return -EINVAL;
    > + }
    > }
    >
    > platform_set_drvdata(pdev, data);
    > @@ -738,14 +759,14 @@ static int mtk_iommu_probe(struct platform_device *pdev)
    > ret = iommu_device_sysfs_add(&data->iommu, dev, NULL,
    > "mtk-iommu.%pa", &ioaddr);
    > if (ret)
    > - return ret;
    > + goto out_link_remove;
    >
    > iommu_device_set_ops(&data->iommu, &mtk_iommu_ops);
    > iommu_device_set_fwnode(&data->iommu, &pdev->dev.of_node->fwnode);
    >
    > ret = iommu_device_register(&data->iommu);
    > if (ret)
    > - return ret;
    > + goto out_sysfs_remove;

    Technically, this change is unrelated.

    >
    > spin_lock_init(&data->tlb_lock);
    > list_add_tail(&data->list, &m4ulist);
    > @@ -754,6 +775,13 @@ static int mtk_iommu_probe(struct platform_device *pdev)
    > bus_set_iommu(&platform_bus_type, &mtk_iommu_ops);
    >
    > return component_master_add_with_match(dev, &mtk_iommu_com_ops, match);
    > +
    > +out_sysfs_remove:
    > + iommu_device_sysfs_remove(&data->iommu);
    > +out_link_remove:
    > + if (dev->pm_domain)
    > + device_link_remove(data->smicomm_dev, dev);
    > + return ret;
    > }
    >
    > static int mtk_iommu_remove(struct platform_device *pdev)
    > @@ -767,6 +795,8 @@ static int mtk_iommu_remove(struct platform_device *pdev)
    > bus_set_iommu(&platform_bus_type, NULL);
    >
    > clk_disable_unprepare(data->bclk);
    > + if (pdev->dev.pm_domain)
    > + device_link_remove(data->smicomm_dev, &pdev->dev);
    > devm_free_irq(&pdev->dev, data->irq, data);
    > component_master_del(&pdev->dev, &mtk_iommu_com_ops);
    > return 0;
    > diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
    > index d0c93652bdbe..5e03a029c4dc 100644
    > --- a/drivers/iommu/mtk_iommu.h
    > +++ b/drivers/iommu/mtk_iommu.h
    > @@ -68,6 +68,7 @@ struct mtk_iommu_data {
    >
    > struct iommu_device iommu;
    > const struct mtk_iommu_plat_data *plat_data;
    > + struct device *smicomm_dev;
    >
    > struct dma_iommu_mapping *mapping; /* For mtk_iommu_v1.c */
    >
    > --
    > 2.18.0
    >

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