How to increase the size of Memory behind bridge

I have NVIDIA AGX orix box, If I do lspci -vvv , memory behind bridge is 4MB, I want to increase in GBs:
Is there anyway to increase the size except setpci command. If I set the bar size using setpci, then after rescan it picks the older value.

0005:00:00.0 PCI bridge: NVIDIA Corporation Device 229a (rev a1) (prog-if 00 [Normal decode])
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- SERR- <PERR- INTx-
Latency: 0
Interrupt: pin A routed to IRQ 68
Bus: primary=00, secondary=01, subordinate=ff, sec-latency=0
I/O behind bridge: 00000000-00000fff [size=4K]
Memory behind bridge: 40000000-403fffff [size=4M]
** Prefetchable memory behind bridge: 0000002740000000-00000027402fffff [size=3M]**
Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ <SERR- <PERR-
BridgeCtl: Parity- SERR+ NoISA- VGA- VGA16- MAbort- >Reset- FastB2B-

Sorry for the late response.
Is this still an issue to support? Any result can be shared?

Yes, still I am trying to find the way to increase memory behind bridge.