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Message-ID: <aTpgAU6FjinhclQH@nvidia.com>
Date: Wed, 10 Dec 2025 22:09:05 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: Robin Murphy <robin.murphy@....com>, Ashish Mhetre <amhetre@...dia.com>
CC: <oe-kbuild-all@...ts.linux.dev>, <thierry.reding@...il.com>,
<jonathanh@...dia.com>, <vdumpa@...dia.com>, <jgg@...pe.ca>,
<linux-arm-kernel@...ts.infradead.org>, <iommu@...ts.linux.dev>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-tegra@...r.kernel.org>, <joro@...tes.org>, <robh@...nel.org>,
<krzk+dt@...nel.org>, <conor+dt@...nel.org>, kernel test robot
<lkp@...el.com>, <will@...nel.org>
Subject: Re: [PATCH V4 1/3] iommu/arm-smmu-v3: Add device-tree support for
CMDQV driver
On Wed, Dec 10, 2025 at 12:39:49PM +0000, Robin Murphy wrote:
> On 2025-12-10 5:19 am, Ashish Mhetre wrote:
> [...]
> > Hi Robin, Nic,
> > We removed ACPI dependency in Kconfig but driver still depends
> > on ACPI for these functions. I will be protecting ACPIspecific
> > tegra241-cmdqv code under CONFIG_ACPI similar to what is done
> > in arm-smmu-v3 driver. Is this the correct thing to do or do you
> > have any other suggestions?
>
> Yes, when I commented that "depends on ACPI || OF" was functionally the same
> as just removing "depends on ACPI", I didn't mean to suggest that wasn't
> necessarily a genuine dependency still.
>
> I guess if you can wrap the ACPI-specific functions in a single #ifdef block
> that's reasonable, however I do now wonder whether things couldn't be
> factored out a bit more - if it's a standard DSDT/SSDT namespace device,
> shouldn't there also be a corresponding platform device created for it,
> which we could look up instead of delving directly into the _CRS of the ACPI
> node itself? (not sure off-hand if there's a straightforward inverse of
> ACPI_COMPANION()...)
Ah, I did a quick tracer at acpi_create_platform_device(). And I
do see platform devices being created. So, we could have made it
ACPI-independent from the beginning, as you expected :)
Ashish, let's attach the following patch in your series:
>From 7b69a638276e66b16b923b0ce1743d3efc85a04c Mon Sep 17 00:00:00 2001
From: Nicolin Chen <nicolinc@...dia.com>
Date: Thu, 11 Dec 2025 05:47:05 +0000
Subject: [PATCH] iommu/tegra241-cmdqv: Decouple driver from ACPI
A platform device is created by acpi_create_platform_device() per CMDQV's
adev. That means there is no point in going through _CRS of ACPI.
Replace all the ACPI functions with standard platform functions. And drop
all ACPI dependencies. This will make the driver compatible with DT also.
Suggested-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
drivers/iommu/arm/Kconfig | 1 -
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +-
.../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 84 +++----------------
3 files changed, 13 insertions(+), 74 deletions(-)
diff --git a/drivers/iommu/arm/Kconfig b/drivers/iommu/arm/Kconfig
index ef42bbe07dbef..5fac08b89deea 100644
--- a/drivers/iommu/arm/Kconfig
+++ b/drivers/iommu/arm/Kconfig
@@ -121,7 +121,6 @@ config ARM_SMMU_V3_KUNIT_TEST
config TEGRA241_CMDQV
bool "NVIDIA Tegra241 CMDQ-V extension support for ARM SMMUv3"
- depends on ACPI
help
Support for NVIDIA CMDQ-Virtualization extension for ARM SMMUv3. The
CMDQ-V extension is similar to v3.3 ECMDQ for multi command queues
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 38028e4a52f7f..0c98be3135c63 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -5280,7 +5280,7 @@ static void acpi_smmu_dsdt_probe_tegra241_cmdqv(struct acpi_iort_node *node,
adev = acpi_dev_get_first_match_dev("NVDA200C", uid, -1);
if (adev) {
/* Tegra241 CMDQV driver is responsible for put_device() */
- smmu->impl_dev = &adev->dev;
+ smmu->impl_dev = acpi_get_first_physical_node(adev);
smmu->options |= ARM_SMMU_OPT_TEGRA241_CMDQV;
dev_info(smmu->dev, "found companion CMDQV device: %s\n",
dev_name(smmu->impl_dev));
diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index 378104cd395e5..1fc03b72beb88 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -3,17 +3,15 @@
#define dev_fmt(fmt) "tegra241_cmdqv: " fmt
-#include <linux/acpi.h>
#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/iommu.h>
#include <linux/iommufd.h>
#include <linux/iopoll.h>
+#include <linux/platform_device.h>
#include <uapi/linux/iommufd.h>
-#include <acpi/acpixf.h>
-
#include "arm-smmu-v3.h"
/* CMDQV register page base and size defines */
@@ -854,69 +852,6 @@ static struct arm_smmu_impl_ops tegra241_cmdqv_impl_ops = {
/* Probe Functions */
-static int tegra241_cmdqv_acpi_is_memory(struct acpi_resource *res, void *data)
-{
- struct resource_win win;
-
- return !acpi_dev_resource_address_space(res, &win);
-}
-
-static int tegra241_cmdqv_acpi_get_irqs(struct acpi_resource *ares, void *data)
-{
- struct resource r;
- int *irq = data;
-
- if (*irq <= 0 && acpi_dev_resource_interrupt(ares, 0, &r))
- *irq = r.start;
- return 1; /* No need to add resource to the list */
-}
-
-static struct resource *
-tegra241_cmdqv_find_acpi_resource(struct device *dev, int *irq)
-{
- struct acpi_device *adev = to_acpi_device(dev);
- struct list_head resource_list;
- struct resource_entry *rentry;
- struct resource *res = NULL;
- int ret;
-
- INIT_LIST_HEAD(&resource_list);
- ret = acpi_dev_get_resources(adev, &resource_list,
- tegra241_cmdqv_acpi_is_memory, NULL);
- if (ret < 0) {
- dev_err(dev, "failed to get memory resource: %d\n", ret);
- return NULL;
- }
-
- rentry = list_first_entry_or_null(&resource_list,
- struct resource_entry, node);
- if (!rentry) {
- dev_err(dev, "failed to get memory resource entry\n");
- goto free_list;
- }
-
- /* Caller must free the res */
- res = kzalloc(sizeof(*res), GFP_KERNEL);
- if (!res)
- goto free_list;
-
- *res = *rentry->res;
-
- acpi_dev_free_resource_list(&resource_list);
-
- INIT_LIST_HEAD(&resource_list);
-
- if (irq)
- ret = acpi_dev_get_resources(adev, &resource_list,
- tegra241_cmdqv_acpi_get_irqs, irq);
- if (ret < 0 || !irq || *irq <= 0)
- dev_warn(dev, "no interrupt. errors will not be reported\n");
-
-free_list:
- acpi_dev_free_resource_list(&resource_list);
- return res;
-}
-
static int tegra241_cmdqv_init_structures(struct arm_smmu_device *smmu)
{
struct tegra241_cmdqv *cmdqv =
@@ -1042,18 +977,23 @@ __tegra241_cmdqv_probe(struct arm_smmu_device *smmu, struct resource *res,
struct arm_smmu_device *tegra241_cmdqv_probe(struct arm_smmu_device *smmu)
{
+ struct platform_device *pdev = to_platform_device(smmu->impl_dev);
struct arm_smmu_device *new_smmu;
- struct resource *res = NULL;
+ struct resource *res;
int irq;
- if (!smmu->dev->of_node)
- res = tegra241_cmdqv_find_acpi_resource(smmu->impl_dev, &irq);
- if (!res)
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "no memory resource found for CMDQV\n");
goto out_fallback;
+ }
- new_smmu = __tegra241_cmdqv_probe(smmu, res, irq);
- kfree(res);
+ irq = platform_get_irq_optional(pdev, 0);
+ if (irq <= 0)
+ dev_warn(&pdev->dev,
+ "no interrupt. errors will not be reported\n");
+ new_smmu = __tegra241_cmdqv_probe(smmu, res, irq);
if (new_smmu)
return new_smmu;
--
2.43.0
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