IMX8 PCIE BAR 15没有空间是怎么回事？

[5.051843] imx6q-pcie 33800000.pcie: 33800000.pcie supply epdev_on not found, using dummy regulator
[5.061724] OF: PCI: host bridge /pcie@0x33800000 ranges:
[ 5.067153] OF: PCI: 没有找到/pcie的总线范围@0x33800000，使用[BUS 00 -FF]
[5.074664]：PCI：IO 0x1FF80000..0x1ff80000..0x1ff8fffff-> 0x00000000
[5.080606] of：PCI：MEM 0x1800000000000000000000,000000..0X1FEFFFFF -FEFFF-> 0x18000000000000000000000000000000000000000000000000000000000000
个使用 EXT REfCLK! 初始化 PHY。
[5.094150]imx6q-pcie 33800000.pcie：PHY初始化结束！。
[5.100322]imx6q-pcie 33800000.pcie:pcie phy pll被锁定。
[ 5.159463] imx6q-pcie 33800000.pcie: Link up, Gen2
[ 5.166360] imx6q-pcie 33800000.pcie: PCI 主桥到总线 0000:00
[5.172753] pci_bus 0000:00:根总线资源[bus 00-ff]
[5.178262]pci_bus 0000:00:根总线资源[io 0x0000-0xffff]
[5.184460]pci_bus 0000:00:根总线资源[mem 0x18000000-0x1fefffff] ]
[ 5.191387] pci 0000:00:00.0: quirk_sprd_pci_resizebar: 不支持调整大小栏
[ 5.210229] pci 0000:00:00.0: BAR 15: [内存大小 0x400000000 pref] [5.217476] pci 0000.0:00AR0
: 15: 无法分配 [mem 大小 0x400000000 pref]
[5.225063] pci 0000:00:00.0: BAR 14: 已分配 [mem 0x18000000-0x187fffff]
[5.231955] pci 0000:00:00.0: BAR 0: 已分配 [mem 08000000-0x187fffff] 64 位]
[ 5.239280] pci 0000:00:00.0: BAR 6: 已分配 [mem 0x18900000-0x1890ffff pref]
[5.246523] pci 0000:01:00.0:BAR 0:[mem size 0x400000000 64bit pref]没有空间[5.254191]pci 0000:01:00.0:BAR 0:无法分配[mem size 0x400000000 64bit pref][
5.262210
] 0000：01：00.0：BAR 2：已分配[mem 0x18000000-0x183fffff 64bit]
[5.269572] pci 0000：01：00.0：BAR 4：已分配[mem 0x18400000-0x187fffff 64bit] [5.276933] pci0：
PCI 0：00到 [bus 01-ff]
[5.282172] pci 0000:00:00.0: 桥接窗口 [mem 0x18000000-0x187fffff]
[5.289429] sprd-pcie-ep-device 0000:00:00.0: ep: probe
[5.294670] sprd-pcie -ep-device 0000:00:00.0: sprd_pcie_iommu_init domian null
[5.301958] sprd-pcie-ep-device 0000:00:00.0: ep: B​​AR[0] [mem 0x18800000-0x188fffff 64bit]
[5.310234]sprd-pcie-ep-device 0000:00:00.0:ep:BAR[1][??? 0x00000000 标志 0x0]
[ 5.317902] sprd-pcie-ep-device 0000:00:00.0: ep: B​​AR[2] [??? 0x00000000 标志 0x0]
[ 5.325568] sprd-pcie-ep-device 0000:00:00.0: ep: B​​AR[3] [??? 0x00000000 标志 0x0]
[ 5.333235] sprd-pcie-ep-device 0000:00:00.0: ep: B​​AR[4] [??? 0x00000000 标志 0x0]
[ 5.340901] sprd-pcie-ep-device 0000:00:00.0: ep: B​​AR[5] [??? 0x00000000 标志 0x0]
[ 5.348569] sprd-pcie-ep-device 0000:00:00.0: 不能 ioremap BAR 4: [??? 0x00000000 标志 0x0]
[ 5.357103] sprd-pcie-ep-device 0000:00:00.0: ep: 无法映射 cfg 栏。
[ 5.363845] sprd-pcie-ep-device: 0000:00:00.0 探测失败，错误为 -12
[ 5.371241] pcieport 0000:00:00.0: 使用 IRQ 233 向 PME 发送信号
[ 5.377110] pcieport 0000:00:00.0: AER 启用 IRQ 233