Re: [RFC PATCH v2 05/11] ACPI: platform: setup MSI domain for ACPI based platform device

From: Hanjun Guo
Date: Thu Sep 15 2016 - 10:07:20 EST

Hi Marc,

Thanks for your review, reply inline.

On 09/14/2016 11:45 PM, Marc Zyngier wrote:
On 14/09/16 15:21, Hanjun Guo wrote:
From: Hanjun Guo <hanjun.guo@xxxxxxxxxx>

With the platform msi domain created, we can set up the msi domain
for a platform device when it's probed.

This patch introduces acpi_configure_msi_domain(), which retrieves
the domain from iort and set it to platform device.

As some platform devices such as an irqchip needs the msi irqdomain
to be the interrupt parent domain, we need to get irqdomain before
platform device is probed.

Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Tomasz Nowicki <tn@xxxxxxxxxxxx>
Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
drivers/acpi/arm64/iort.c | 5 ++++-
drivers/base/platform-msi.c | 15 ++++++++++++++-
drivers/base/platform.c | 2 ++
include/linux/msi.h | 1 +
4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 13a1905..bccd3cc 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -478,6 +478,7 @@ struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id)
struct fwnode_handle *handle;
int its_id;
+ enum irq_domain_bus_token bus_token;

if (iort_dev_find_its_id(dev, req_id, 0, &its_id))
return NULL;
@@ -486,7 +487,9 @@ struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id)
if (!handle)
return NULL;

- return irq_find_matching_fwnode(handle, DOMAIN_BUS_PCI_MSI);
+ bus_token = dev_is_pci(dev) ?
+ return irq_find_matching_fwnode(handle, bus_token);

static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
diff --git a/drivers/base/platform-msi.c b/drivers/base/platform-msi.c
index 279e539..f6eae18 100644
--- a/drivers/base/platform-msi.c
+++ b/drivers/base/platform-msi.c
@@ -17,8 +17,8 @@
* along with this program. If not, see <>.

+#include <linux/acpi_iort.h>
#include <linux/device.h>
-#include <linux/idr.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/msi.h>
@@ -416,3 +416,16 @@ int platform_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,

return err;
+int acpi_configure_msi_domain(struct device *dev)
+ struct irq_domain *d = NULL;
+ d = iort_get_device_domain(dev, 0);

This looks completely wrong. Why RID 0? As far as I can see, 0 is not a
special value, and could be something else.

You are right. I tried to reuse the API of get irqdomain in IORT for
PCI devices, but for platform device, we don't have req id in named
component, so I just pass 0 here, I think I need to prepare another
API for platform devices.

+ if (d) {
+ dev_set_msi_domain(dev, d);
+ return 0;
+ }
+ return -EINVAL;

I really hate this, as the platform MSI code is intentionally free of
any firmware reference. This should live in the ACPI code.

Will do, I think locate it in iort.c is better.

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 6482d47..ea01a37 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -24,6 +24,7 @@
#include <linux/pm_domain.h>
#include <linux/idr.h>
#include <linux/acpi.h>
+#include <linux/msi.h>
#include <linux/clk/clk-conf.h>
#include <linux/limits.h>
#include <linux/property.h>
@@ -500,6 +501,7 @@ struct platform_device *platform_device_register_full(
pdev->dev.parent = pdevinfo->parent;
pdev->dev.fwnode = pdevinfo->fwnode;

+ acpi_configure_msi_domain(&pdev->dev);

It feels odd to put this in the generic code, while you could perfectly
put the call into acpi_platform.c and keep the firmware stuff away from
the generic code.

My feeling is the same, I'm still trying to find a new way to do it,
but I can't simply put that in acpi_platform.c, because

platform_device_alloc() --> dev is alloced
dev.fwnode is set
(I get the msi domain by the fwnode in acpi_configure_msi_domain)
platform_device_add() --> which the device is probed.

For devices like irqchip which needs the dev->msi_domain to be
set before it's really probed, because it needs the msi domain
to be the parent domain.

If I call the function in acpi_create_platform_device() before
platform_device_register_full(), we just can't set dev's msi
domain, but if call it after platform_device_register_full(),
the irqchip like mbigen will not get its parent domain...

DT is using another API for platform device probe, so has no
problems like I said above, any suggestions to do it right in