2020-09-30 08:51:23

by Nicolin Chen

Subject: [PATCH v3 3/3] iommu/tegra-smmu: Add PCI support

This patch simply adds support for PCI devices.

Signed-off-by: Nicolin Chen <[email protected]>
---

Changelog
v2->v3
* Replaced ternary conditional operator with if-else in .device_group()
* Dropped change in tegra_smmu_remove()
v1->v2
* Added error-out labels in tegra_smmu_probe()
* Dropped pci_request_acs() since IOMMU core would call it.

drivers/iommu/tegra-smmu.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 636dc3b89545..db98ca334eae 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -10,6 +10,7 @@
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_device.h>
+#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
@@ -882,7 +883,11 @@ static struct iommu_group *tegra_smmu_device_group(struct device *dev)
group->smmu = smmu;
group->soc = soc;

- group->group = iommu_group_alloc();
+ if (dev_is_pci(dev))
+ group->group = pci_device_group(dev);
+ else
+ group->group = generic_device_group(dev);
+
if (IS_ERR(group->group)) {
devm_kfree(smmu->dev, group);
mutex_unlock(&smmu->lock);
@@ -1079,22 +1084,34 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
iommu_device_set_fwnode(&smmu->iommu, dev->fwnode);

err = iommu_device_register(&smmu->iommu);
- if (err) {
- iommu_device_sysfs_remove(&smmu->iommu);
- return ERR_PTR(err);
- }
+ if (err)
+ goto err_sysfs;

err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
- if (err < 0) {
- iommu_device_unregister(&smmu->iommu);
- iommu_device_sysfs_remove(&smmu->iommu);
- return ERR_PTR(err);
+ if (err < 0)
+ goto err_unregister;
+
+#ifdef CONFIG_PCI
+ if (!iommu_present(&pci_bus_type)) {
+ err = bus_set_iommu(&pci_bus_type, &tegra_smmu_ops);
+ if (err < 0)
+ goto err_bus_set;
}
+#endif

if (IS_ENABLED(CONFIG_DEBUG_FS))
tegra_smmu_debugfs_init(smmu);

return smmu;
+
+err_bus_set:
+ bus_set_iommu(&platform_bus_type, NULL);
+err_unregister:
+ iommu_device_unregister(&smmu->iommu);
+err_sysfs:
+ iommu_device_sysfs_remove(&smmu->iommu);
+
+ return ERR_PTR(err);
}

void tegra_smmu_remove(struct tegra_smmu *smmu)
--
2.17.1

2020-09-30 14:56:26

by Dmitry Osipenko

Subject: Re: [PATCH v3 3/3] iommu/tegra-smmu: Add PCI support

...
> +#ifdef CONFIG_PCI
> + if (!iommu_present(&pci_bus_type)) {


In the previous reply you said that you're borrowing this check from the
arm-smmu driver, but arm-smmu also has a similar check for
platform_bus_type, while Tegra SMMU driver doesn't have it. Hence I'm
objecting the necessity of having this check.

Please give a rationale for having this check in the code. And please
note that cargo cult isn't a rationale to me.

2020-09-30 20:10:34

by Nicolin Chen

Subject: Re: [PATCH v3 3/3] iommu/tegra-smmu: Add PCI support

On Wed, Sep 30, 2020 at 05:53:20PM +0300, Dmitry Osipenko wrote:
> ...
> > +#ifdef CONFIG_PCI
> > + if (!iommu_present(&pci_bus_type)) {
>
>
> In the previous reply you said that you're borrowing this check from the
> arm-smmu driver, but arm-smmu also has a similar check for
> platform_bus_type, while Tegra SMMU driver doesn't have it. Hence I'm
> objecting the necessity of having this check.
>
> Please give a rationale for having this check in the code. And please
> note that cargo cult isn't a rationale to me.

Okay, okay....I will remove it upon testing.