Subject: [PATCH v5 1/4] PCI: X-Gene: Add the APM X-Gene v1 PCIe MSI/MSIX termination driver

From: [email-masked] (Marc Zyngier)
Date: Tue, 21 Apr 2015 16:08:45 +0100

On 21/04/15 05:04, Duc Dang wrote:
> X-Gene v1 SoC supports total 256 MSI/MSIX vectors coalesced into
> 16 HW IRQ lines.

This commit message could be beefed up to describe what this really does.

> Signed-off-by: Duc Dang <[email-masked]>
> Signed-off-by: Tanmay Inamdar <[email-masked]>
> ---
>  drivers/pci/host/Kconfig         |   6 +
>  drivers/pci/host/Makefile        |   1 +
>  drivers/pci/host/pci-xgene-msi.c | 477 +++++++++++++++++++++++++++++++++++++++
>  drivers/pci/host/pci-xgene.c     |  21 ++
>  4 files changed, 505 insertions(+)
>  create mode 100644 drivers/pci/host/pci-xgene-msi.c
> 
> diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
> index 7b892a9..c9b61fa 100644
> --- a/drivers/pci/host/Kconfig
> +++ b/drivers/pci/host/Kconfig
> @@ -89,11 +89,17 @@ config PCI_XGENE
>         depends on ARCH_XGENE
>         depends on OF
>         select PCIEPORTBUS
> +       select PCI_MSI_IRQ_DOMAIN if PCI_MSI
> +       select PCI_XGENE_MSI if PCI_MSI
>         help
>           Say Y here if you want internal PCI support on APM X-Gene SoC.
>           There are 5 internal PCIe ports available. Each port is GEN3 capable
>           and have varied lanes from x1 to x8.
> 
> +config PCI_XGENE_MSI
> +       bool "X-Gene v1 PCIe MSI feature"
> +       depends on PCI_XGENE && PCI_MSI
> +
>  config PCI_LAYERSCAPE
>         bool "Freescale Layerscape PCIe controller"
>         depends on OF && ARM
> diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
> index e61d91c..f39bde3 100644
> --- a/drivers/pci/host/Makefile
> +++ b/drivers/pci/host/Makefile
> @@ -11,5 +11,6 @@ obj-$(CONFIG_PCIE_SPEAR13XX) += pcie-spear13xx.o
>  obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone-dw.o pci-keystone.o
>  obj-$(CONFIG_PCIE_XILINX) += pcie-xilinx.o
>  obj-$(CONFIG_PCI_XGENE) += pci-xgene.o
> +obj-$(CONFIG_PCI_XGENE_MSI) += pci-xgene-msi.o
>  obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
>  obj-$(CONFIG_PCI_VERSATILE) += pci-versatile.o
> diff --git a/drivers/pci/host/pci-xgene-msi.c b/drivers/pci/host/pci-xgene-msi.c
> new file mode 100644
> index 0000000..910f5db
> --- /dev/null
> +++ b/drivers/pci/host/pci-xgene-msi.c
> @@ -0,0 +1,477 @@
> +/*
> + * APM X-Gene MSI Driver
> + *
> + * Copyright (c) 2014, Applied Micro Circuits Corporation
> + * Author: Tanmay Inamdar <[email-masked]>
> + *        Duc Dang <[email-masked]>
> + *
> + * This program is free software; you can redistribute  it and/or modify it
> + * under  the terms of  the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the  License, or (at your
> + * option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/of_irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/of_pci.h>
> +
> +#define MSI_IR0                        0x000000
> +#define MSI_INT0               0x800000
> +#define IDX_PER_GROUP          8
> +#define IRQS_PER_IDX           16
> +#define NR_HW_IRQS             16
> +#define NR_MSI_VEC             (IDX_PER_GROUP * IRQS_PER_IDX * NR_HW_IRQS)
> +
> +struct xgene_msi {
> +       struct device_node              *node;
> +       struct msi_controller           mchip;
> +       struct irq_domain               *domain;
> +       u64                             msi_addr;
> +       void __iomem                    *msi_regs;
> +       unsigned long                   *bitmap;
> +       struct mutex                    bitmap_lock;
> +       int                             *msi_virqs;
> +       int                             num_cpus;
> +};
> +
> +static struct irq_chip xgene_msi_top_irq_chip = {
> +       .name           = "X-Gene1 MSI",
> +       .irq_enable     = pci_msi_unmask_irq,
> +       .irq_disable    = pci_msi_mask_irq,
> +       .irq_mask       = pci_msi_mask_irq,
> +       .irq_unmask     = pci_msi_unmask_irq,
> +};
> +
> +static struct  msi_domain_info xgene_msi_domain_info = {
> +       .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> +                 MSI_FLAG_PCI_MSIX),
> +       .chip   = &xgene_msi_top_irq_chip,
> +};
> +
> +/*
> + * X-Gene v1 has 16 groups of MSI termination registers MSInIRx, where
> + * n is group number (0..F), x is index of registers in each group (0..7)
> + * The registers layout is like following:
> + * MSI0IR0                     base_addr
> + * MSI0IR1                     base_addr +  0x10000
> + * ...                         ...
> + * MSI0IR6                     base_addr +  0x60000
> + * MSI0IR7                     base_addr +  0x70000
> + * MSI1IR0                     base_addr +  0x80000
> + * MSI1IR1                     base_addr +  0x90000
> + * ...                         ...
> + * MSI1IR7                     base_addr +  0xF0000
> + * MSI2IR0                     base_addr + 0x100000
> + * ...                         ...
> + * MSIFIR0                     base_addr + 0x780000
> + * MSIFIR1                     base_addr + 0x790000
> + * ...                         ...
> + * MSIFIR7                     base_addr + 0x7F0000
> + *
> + * Each index register support 16 MSI vectors (0..15) to generate interrupt.
> + * There are total 16 GIC IRQs assigned for these 16 groups of MSI termination
> + * registers.
> + *
> + * With 2048 MSI vectors supported, the MSI message can be construct using
> + * following scheme:
> + * - Divide into 8 256-vector groups
> + *             Group 0: 0-255
> + *             Group 1: 256-511
> + *             Group 2: 512-767
> + *             ...
> + *             Group 7: 1792-2047
> + * - Each 256-vector group is divided into 16 16-vector groups
> + *     As an example: 16 16-vector groups for 256-vector group 0-255 is
> + *             Group 0: 0-15
> + *             Group 1: 16-32
> + *             ...
> + *             Group 15: 240-255
> + * - The termination address of MSI vector in 256-vector group n and 16-vector
> + * group x is the address of MSIxIRn
> + * - The data for MSI vector in 16-vector group x is x
> + */
> +static void xgene_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +       struct xgene_msi *msi = irq_data_get_irq_chip_data(data);
> +       u32 reg_set = data->hwirq / (NR_HW_IRQS * IRQS_PER_IDX);
> +       u32 group = data->hwirq % NR_HW_IRQS;
> +
> +       msg->address_hi = upper_32_bits(msi->msi_addr);
> +       msg->address_lo = lower_32_bits(msi->msi_addr) +
> +                         (((8 * group) + reg_set) << 16);
> +       msg->data = (data->hwirq / NR_HW_IRQS) % IRQS_PER_IDX;
> +}
> +
> +/*
> + * X-Gene v1 only has 16 MSI GIC IRQs for 2048 MSI vectors.
> + * To maintain the expected behaviour of .set_affinity for each MSI
> + * interrupt, the 16 MSI GIC IRQs are statically allocate to 8 X-Gene
                                              nit: allocated
> + * v1 cores (2 GIC IRQs for each cores). The MSI vector is moved fom 1
                                nit: core
> + * MSI GIC IRQ to another MSI GIC IRQ to steer its MSI interrupt to
> + * correct X-Gene v1 core. As a consequence, the total MSI vectors that
> + * X-Gene v1 supports will be reduced to 256 (2048/8) vectors.
> + */
> +static int xgene_msi_set_affinity(struct irq_data *irq_data,
> +                                 const struct cpumask *mask, bool force)
> +{
> +       struct xgene_msi *msi = irq_data_get_irq_chip_data(irq_data);
> +       struct msi_desc *desc = irq_get_msi_desc(irq_data->irq);
> +       int target_cpu = cpumask_first(mask);
> +       int curr_cpu;
> +       struct msi_msg msg;
> +       u32 reg_set, group;
> +
> +       if (!desc)
> +               return IRQ_SET_MASK_OK_DONE;

That can't be right. You really should return an error code here.

> +       curr_cpu = (irq_data->hwirq % NR_HW_IRQS) % msi->num_cpus;
> +       if (curr_cpu == target_cpu)
> +               return IRQ_SET_MASK_OK_DONE;
> +
> +       irq_data->hwirq = irq_data->hwirq + (target_cpu - curr_cpu);
> +       reg_set = irq_data->hwirq / (NR_HW_IRQS * IRQS_PER_IDX);
> +       group = irq_data->hwirq % NR_HW_IRQS;
> +
> +       /* Prepare new MSI msg to steer MSI to target CPU */
> +       msg.address_hi = upper_32_bits(msi->msi_addr);
> +       msg.address_lo = lower_32_bits(msi->msi_addr) +
> +               (((8 * group) + reg_set) << 16);
> +       msg.data = (irq_data->hwirq / NR_HW_IRQS) % IRQS_PER_IDX;
> +       /*
> +        * Write new MSI termination address and data into
> +        * PCIe device configuration space
> +        */
> +       pci_write_msi_msg(irq_data->irq, &msg);
> +       return IRQ_SET_MASK_OK_DONE;

That feels like the wrong thing to do. You are duplicating a
functionality that already exists in msi_domain_set_affinity.

You should probably just update hwirq to reflect the new absolute MSI
number, return IRQ_SET_MASK_OK and let compose_msi_msg/write_msi_msg do
the right thing.

> +}
> +
> +static struct irq_chip xgene_msi_bottom_irq_chip = {
> +       .name                   = "MSI",
> +       .irq_set_affinity       = xgene_msi_set_affinity,
> +       .irq_compose_msi_msg    = xgene_compose_msi_msg,
> +};
> +
> +static int xgene_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
> +                                 unsigned int nr_irqs, void *args)
> +{
> +       struct xgene_msi *msi = domain->host_data;
> +       int msi_irq;
> +       int i;
> +
> +       mutex_lock(&msi->bitmap_lock);
> +
> +       msi_irq = find_first_zero_bit(msi->bitmap, NR_MSI_VEC);
> +       if (msi_irq < NR_MSI_VEC)
> +               set_bit(msi_irq, msi->bitmap);
> +       else
> +               msi_irq = -ENOSPC;
> +
> +       /* Check if we found a valid MSI */
> +       if ((msi_irq >= 0) && ((msi_irq % msi->num_cpus) == 0)) {
> +               /* Allocate other vectors as well */
> +               for (i = 1; i < msi->num_cpus; i++) {
> +                       if ((msi_irq + i) >= NR_MSI_VEC) {
> +                               msi_irq = -ENOSPC;
> +                               break;

Eh? Right in the middle of the allocation? You end up with an
inconsistent bitmap, don't you?

Consider using bitmap_find_next_zero_area() to allocate a chunk of 8
consecutive bits, which will give you the MSI for your 8 CPUs.

> +                       }
> +                       if (!test_bit((msi_irq + i), msi->bitmap))
> +                               set_bit(msi_irq + i, msi->bitmap);
> +                       else {
> +                               msi_irq = -ENOSPC;
> +                               break;

Same breakage.

> +                       }
> +               }
> +       }
> +
> +       mutex_unlock(&msi->bitmap_lock);
> +
> +       if (msi_irq < 0)
> +               return msi_irq;
> +
> +       irq_domain_set_info(domain, virq, msi_irq,
> +                           &xgene_msi_bottom_irq_chip, domain->host_data,
> +                           handle_simple_irq, NULL, NULL);
> +       set_irq_flags(virq, IRQF_VALID);
> +
> +       return 0;
> +}
> +
> +static void xgene_irq_domain_free(struct irq_domain *domain,
> +                                 unsigned int virq, unsigned int nr_irqs)
> +{
> +       struct irq_data *d = irq_domain_get_irq_data(domain, virq);
> +       struct xgene_msi *msi = irq_data_get_irq_chip_data(d);
> +       int i;
> +       u32 hwirq;
> +
> +       mutex_lock(&msi->bitmap_lock);
> +
> +       hwirq = d->hwirq - (d->hwirq % msi->num_cpus);
> +       for (i = 0; i < msi->num_cpus; i++)
> +               if (test_bit(hwirq + i, msi->bitmap))
> +                       clear_bit(hwirq + i, msi->bitmap);

bitmap_release_region()?

> +       mutex_unlock(&msi->bitmap_lock);
> +
> +       irq_domain_free_irqs_parent(domain, virq, nr_irqs);
> +}
> +
> +static const struct irq_domain_ops msi_domain_ops = {
> +       .alloc  = xgene_irq_domain_alloc,
> +       .free   = xgene_irq_domain_free,
> +};
> +
> +static int xgene_allocate_domains(struct xgene_msi *msi)
> +{
> +       msi->domain = irq_domain_add_linear(NULL, NR_MSI_VEC,
> +                                           &msi_domain_ops, msi);
> +       if (!msi->domain)
> +               return -ENOMEM;
> +
> +       msi->mchip.of_node = msi->node;
> +       msi->mchip.domain = pci_msi_create_irq_domain(msi->mchip.of_node,
> +                                                     &xgene_msi_domain_info,
> +                                                     msi->domain);
> +
> +       if (!msi->mchip.domain) {
> +               irq_domain_remove(msi->domain);
> +               return -ENOMEM;
> +       }
> +
> +       return 0;
> +}
> +
> +static void xgene_free_domains(struct xgene_msi *msi)
> +{
> +       if (msi->mchip.domain)
> +               irq_domain_remove(msi->mchip.domain);
> +       if (msi->domain)
> +               irq_domain_remove(msi->domain);
> +}
> +
> +static int xgene_msi_init_allocator(struct xgene_msi *xgene_msi)
> +{
> +       int size = BITS_TO_LONGS(NR_MSI_VEC) * sizeof(long);
> +
> +       xgene_msi->bitmap = kzalloc(size, GFP_KERNEL);
> +       if (!xgene_msi->bitmap)
> +               return -ENOMEM;
> +
> +       mutex_init(&xgene_msi->bitmap_lock);
> +
> +       xgene_msi->msi_virqs = kcalloc(NR_HW_IRQS, sizeof(int), GFP_KERNEL);
> +       if (!xgene_msi->msi_virqs)
> +               return -ENOMEM;
> +
> +       return 0;
> +}
> +
> +static void xgene_msi_isr(unsigned int irq, struct irq_desc *desc)
> +{
> +       struct irq_chip *chip = irq_desc_get_chip(desc);
> +       struct xgene_msi *xgene_msi;
> +       unsigned int virq;
> +       int msir_index, msir_reg, msir_val, hw_irq;
> +       u32 intr_index, grp_select, msi_grp, processed = 0;
> +
> +       chained_irq_enter(chip, desc);
> +
> +       xgene_msi = irq_desc_get_handler_data(desc);
> +
> +       msi_grp = irq - xgene_msi->msi_virqs[0];

Arghh. Absolutely nothing guarantees that your 16 IRQs are contiguous in
the virtual space. This only works by pure luck. Why don't you use the
handler data to contain your group? Here, you're storing you xgene_msi
structure, which is unique anyway.

> +       if (msi_grp >= NR_HW_IRQS) {
> +               chained_irq_exit(chip, desc);
> +               return;
> +       }
> +
> +       /*
> +        * MSIINTn (n is 0..F) indicates if there is a pending MSI interrupt
> +        * If bit x of this register is set (x is 0..7), one or more interupts
> +        * corresponding to MSInIRx is set.
> +        */
> +       grp_select = readl(xgene_msi->msi_regs + MSI_INT0 + (msi_grp << 16));

Can't you use readl_relaxed?

> +       while (grp_select) {
> +               msir_index = ffs(grp_select) - 1;
> +               /*
> +                * Calculate MSInIRx address to read to check for interrupts
> +                * (refer to termination address and data assignment
> +                * described in xgene_compose_msi_msg function)
> +                */
> +               msir_reg = (msi_grp << 19) + (msir_index << 16);
> +               msir_val = readl(xgene_msi->msi_regs + MSI_IR0 + msir_reg);

Same here?

> +               while (msir_val) {
> +                       intr_index = ffs(msir_val) - 1;
> +                       /*
> +                        * Calculate MSI vector number (refer to the termination
> +                        * address and data assignment described in
> +                        * xgene_compose_msi_msg function)
> +                        */
> +                       hw_irq = (((msir_index * IRQS_PER_IDX) + intr_index) *
> +                                NR_HW_IRQS) + msi_grp;
> +                       hw_irq = hw_irq - (hw_irq % xgene_msi->num_cpus);
> +                       virq = irq_find_mapping(xgene_msi->domain, hw_irq);

Maybe a comment indicating that the domain is always looked up with the
hwirq as seen from CPU0?

> +                       if (virq != 0)
> +                               generic_handle_irq(virq);
> +                       msir_val &= ~(1 << intr_index);
> +                       processed++;

What's the purpose of processed? Seems fairly useless to me.

> +               }
> +               grp_select &= ~(1 << msir_index);
> +       }
> +
> +       chained_irq_exit(chip, desc);
> +}
> +
> +static int xgene_msi_remove(struct platform_device *pdev)
> +{
> +       int virq, i;
> +       struct xgene_msi *msi = platform_get_drvdata(pdev);
> +
> +       for (i = 0; i < NR_HW_IRQS; i++) {
> +               virq = msi->msi_virqs[i];
> +               if (virq != 0)

Under which circumstances could that be zero?

> +                       free_irq(virq, msi);
> +       }
> +
> +       kfree(msi->bitmap);
> +       msi->bitmap = NULL;
> +
> +       xgene_free_domains(msi);

Who frees msi->msi_virqs?

> +       return 0;
> +}
> +
> +static int xgene_msi_setup_hwirq(struct xgene_msi *msi,
> +                                struct platform_device *pdev,
> +                                int irq_index)
> +{
> +       int virt_msir;
> +       cpumask_var_t mask;
> +       int err;
> +
> +       virt_msir = platform_get_irq(pdev, irq_index);
> +       if (virt_msir < 0) {
> +               dev_err(&pdev->dev, "Cannot translate IRQ index %d\n",
> +                       irq_index);
> +               return -EINVAL;
> +       }
> +
> +       irq_set_chained_handler(virt_msir, xgene_msi_isr);
> +       err = irq_set_handler_data(virt_msir, msi);
> +       if (err) {
> +               dev_err(&pdev->dev, "request irq failed\n");
> +               return err;
> +       }
> +
> +       /*
> +        * Statically allocate MSI GIC IRQs to each CPU core
> +        * With 8-core X-Gene v1, 2 MSI GIC IRQs are allocated
> +        * to each core.
> +        */
> +       if (alloc_cpumask_var(&mask, GFP_KERNEL)) {
> +               cpumask_clear(mask);
> +               cpumask_set_cpu(irq_index % msi->num_cpus, mask);
> +               irq_set_affinity(virt_msir, mask);

How about testing the return value of irq_set_affinity?

> +               free_cpumask_var(mask);
> +       }
> +
> +       msi->msi_virqs[irq_index] = virt_msir;
> +
> +       return 0;
> +}
> +
> +static const struct of_device_id xgene_msi_match_table[] = {
> +       {.compatible = "apm,xgene1-msi"},
> +       {},
> +};
> +
> +static int xgene_msi_probe(struct platform_device *pdev)
> +{
> +       struct resource *res;
> +       int rc, irq_index;
> +       struct device_node *np;
> +       const struct of_device_id *matched_np;
> +       struct xgene_msi *xgene_msi;
> +
> +       np = of_find_matching_node_and_match(NULL,
> +                            xgene_msi_match_table, &matched_np);
> +       if (!np)
> +               return -ENODEV;

This is getting silly, really. You already have the device node pointed
to by pdev...

> +
> +       xgene_msi = kzalloc(sizeof(struct xgene_msi), GFP_KERNEL);
> +       if (!xgene_msi) {
> +               dev_err(&pdev->dev, "failed to allocate X-Gene MSI data\n");
> +               return -ENOMEM;
> +       }
> +
> +       xgene_msi->node = np;
> +
> +       platform_set_drvdata(pdev, xgene_msi);
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       xgene_msi->msi_regs = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(xgene_msi->msi_regs)) {
> +               dev_err(&pdev->dev, "no reg space\n");
> +               rc = -EINVAL;
> +               goto error;
> +       }
> +       xgene_msi->msi_addr = res->start;
> +
> +       xgene_msi->num_cpus = num_online_cpus();

How are you going to support CPU hotplug? This probably should be
num_possible_cpus(), and you will need a CPU notifier to handle CPUs
being brought up.

> +       rc = xgene_msi_init_allocator(xgene_msi);
> +       if (rc) {
> +               dev_err(&pdev->dev, "Error allocating MSI bitmap\n");
> +               goto error;
> +       }
> +
> +       rc = xgene_allocate_domains(xgene_msi);
> +       if (rc) {
> +               dev_err(&pdev->dev, "Failed to allocate MSI domain\n");
> +               goto error;
> +       }
> +
> +       for (irq_index = 0; irq_index < NR_HW_IRQS; irq_index++) {
> +               rc = xgene_msi_setup_hwirq(xgene_msi, pdev, irq_index);
> +               if (rc)
> +                       goto error;
> +       }
> +
> +       rc = of_pci_msi_chip_add(&xgene_msi->mchip);
> +       if (rc) {
> +               dev_err(&pdev->dev, "failed to add MSI controller chip\n");
> +               goto error;
> +       }
> +
> +       dev_info(&pdev->dev, "APM X-Gene PCIe MSI driver loaded\n");
> +
> +       return 0;
> +error:
> +       xgene_msi_remove(pdev);
> +       return rc;
> +}
> +
> +static struct platform_driver xgene_msi_driver = {
> +       .driver = {
> +               .name = "xgene-msi",
> +               .owner = THIS_MODULE,
> +               .of_match_table = xgene_msi_match_table,
> +       },
> +       .probe = xgene_msi_probe,
> +       .remove = xgene_msi_remove,
> +};
> +
> +static int __init xgene_pcie_msi_init(void)
> +{
> +       return platform_driver_register(&xgene_msi_driver);
> +}
> +subsys_initcall(xgene_pcie_msi_init);
> +
> diff --git a/drivers/pci/host/pci-xgene.c b/drivers/pci/host/pci-xgene.c
> index 22751ed..3e6faa1 100644
> --- a/drivers/pci/host/pci-xgene.c
> +++ b/drivers/pci/host/pci-xgene.c
> @@ -468,6 +468,23 @@ static int xgene_pcie_setup(struct xgene_pcie_port *port,
>         return 0;
>  }
> 
> +static int xgene_pcie_msi_enable(struct pci_bus *bus)
> +{
> +       struct device_node *msi_node;
> +
> +       msi_node = of_parse_phandle(bus->dev.of_node,
> +                                       "msi-parent", 0);
> +       if (!msi_node)
> +               return -ENODEV;
> +
> +       bus->msi = of_pci_find_msi_chip_by_node(msi_node);
> +       if (bus->msi)
> +               bus->msi->dev = &bus->dev;
> +       else
> +               return -ENODEV;
> +       return 0;
> +}
> +
>  static int xgene_pcie_probe_bridge(struct platform_device *pdev)
>  {
>         struct device_node *dn = pdev->dev.of_node;
> @@ -504,6 +521,10 @@ static int xgene_pcie_probe_bridge(struct platform_device *pdev)
>         if (!bus)
>                 return -ENOMEM;
> 
> +       if (IS_ENABLED(CONFIG_PCI_MSI))
> +               if (xgene_pcie_msi_enable(bus))
> +                       dev_info(port->dev, "failed to enable MSI\n");
> +
>         pci_scan_child_bus(bus);
>         pci_assign_unassigned_bus_resources(bus);
>         pci_bus_add_devices(bus);
> --
> 1.9.1
> 

Looks like there is some more work to do...

	M.
-- 
Jazz is not dead. It just smells funny...