[PATCH v10] PCI: tango: Add MSI controller support

On 24/08/2017 19:04, Bjorn Helgaas wrote:

On Tue, Aug 22, 2017 at 09:03:41PM +0100, Marc Zyngier wrote:

quoted

Marc Gonzalez wrote:

quoted

On 22/08/2017 18:29, Marc Zyngier wrote:

quoted

On 22/08/17 15:56, Marc Gonzalez wrote:

quoted

 #define SMP8759_MUX		0x48
 #define SMP8759_TEST_OUT	0x74
+#define SMP8759_STATUS		0x80
+#define SMP8759_ENABLE		0xa0
+#define SMP8759_DOORBELL	0xa002e07c

Why is this hardcoded and not coming from the device-tree, just like any
other address property?

Since this bus address is software-configurable, I didn't think
it belonged in the DT. Also, I didn't see anything similar in
other binding docs, especially

Documentation/devicetree/bindings/interrupt-controller/msi.txt

If that's software configurable, how on Earth did you pick the address?
How do you ensure that it doesn't conflict with DMA? How is it
configured into the RC?

But we *do* need to resolve this.  This does seem like an address that
shouldn't be hard-coded into the driver.  Since this driver is
programming the address into an MSI message, but not into the receiver
of that message, there's a coordination issue between this driver and
whatever other software does that receiver configuration.

OK. I'll move the doorbell address to the DT for v11.

What property should be used for this address?

sigma,doorbell ?

Or maybe I can put it in reg, since I have a 1:1 mapping
between bus and cpu addresses?

git grep -i doorbell arch/arm/boot/dts/ arch/arm64/boot/dts/
returns nothing.

Regards.