RE: [PATCH v2 04/15] PCI: xilinx: Don't allocate extra memory for the MSI capture address

Thanks Marc for the patch.

Subject: [PATCH v2 04/15] PCI: xilinx: Don't allocate extra memory for the
MSI capture address

A long cargo-culted behaviour of PCI drivers is to allocate memory to obtain
an address that is fed to the controller as the MSI capture address (i.e. the
MSI doorbell).

But there is no actual requirement for this address to be RAM.
All it needs to be is a suitable aligned address that will
*not* be DMA'd to.

Use the physical address of the 'port' data structure as the MSI capture
address.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/pci/controller/pcie-xilinx.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

...

-	msg.address_hi = 0;
-	msg.address_lo = msg_addr;
+	msg.address_hi = upper_32_bits(msg_addr);
+	msg.address_lo = lower_32_bits(msg_addr);

The XILINX_PCIE_REG_MSIBASE2 register expects 4KB aligned address.
The lower 12-bits are always set to 0 in this register. So we need to mask the address 
while programming address to EP.

#define XILINX_PCIE_MSI_ADDR_MASK       GENMASK(31, 12)
msg.address_lo = lower_32_bits(msg_addr) & XILINX_PCIE_MSI_ADDR_MASK;

 	msg.data = irq;

Regards,
Bharat