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

[Hanjun Guo]

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) ?
> > +			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