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

From: [email-masked] (Hanjun Guo)
Date: Thu, 15 Sep 2016 22:05:34 +0800

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 <[email-masked]>
>>
>> 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 <[email-masked]>
>> Cc: Greg KH <[email-masked]>
>> Cc: Thomas Gleixner <[email-masked]>
>> Cc: Bjorn Helgaas <[email-masked]>
>> Cc: Lorenzo Pieralisi <[email-masked]>
>> Cc: Tomasz Nowicki <[email-masked]>
>> Signed-off-by: Hanjun Guo <[email-masked]>
>> ---
>>   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) ?
>> +			DOMAIN_BUS_PCI_MSI : DOMAIN_BUS_PLATFORM_MSI;
>> +	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 <http://www.gnu.org/licenses/>.
>>    */
>>
>> +#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

acpi_create_platform_device()
    platform_device_register_full()
	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
ACPI?

Thanks
Hanjun