使用 pci_enable_msi_block

我正在尝试在内核模块中启用多个 MSI irq 线。我正在 RC 模式下操作。问题是当我打电话时pci_enable_msi_block()它不会分配超过 1 个 MSI。如果我打电话pci_enable_msi_block(dev, 32)它将返回 4（我认为这应该意味着我可以使用 4 个 MSI）。然后我打电话pci_enable_msi_block(dev,4)它返回 1。

这是一个输出$lspci -v after insmod Custom_module.ko但仅成功启用 1 个 MSI

00:00.0 PCI bridge: Texas Instruments Device 8888 (rev 01) (prog-if 00 [Normal decode])
    Flags: bus master, fast devsel, latency 0
    Memory at <ignored> (32-bit, non-prefetchable)
    Memory at <ignored> (32-bit, prefetchable)
    Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
    I/O behind bridge: 00001000-00001fff
    Memory behind bridge: 50000000-501fffff
    Prefetchable memory behind bridge: 50200000-503fffff
    Capabilities: [40] Power Management version 3
    Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
    Capabilities: [70] Express Root Port (Slot-), MSI 00
    Capabilities: [100] Advanced Error Reporting
    Kernel driver in use: pcieport

01:00.0 Memory controller: Xilinx Corporation Device 7022
    Subsystem: Xilinx Corporation Device 0007
    Flags: bus master, fast devsel, latency 0, IRQ 576
    Memory at 50000000 (32-bit, non-prefetchable) [size=1M]
    Capabilities: [80] Power Management version 3
    Capabilities: [90] MSI: Enable+ Count=4/4 Maskable- 64bit+
    Capabilities: [c0] Express Endpoint, MSI 00
    Capabilities: [100] Advanced Error Reporting
    Kernel driver in use: Custom_Module

我该如何使用超过 1 个 MSI。我可以使用 JTAG 编辑 Enable_MSI 寄存器，然后 EP 可以触发 MSI，但没有专用于这些 IRQ 的处理程序。