BUG: SiFive Unmatched: BAR0 on video card is never initialized

[Heinrich Schuchardt]

Am 19. November 2024 21:45:39 MEZ schrieb Yuri Zaporozhets <yuriz at vodafonemail.de>:
>Hi Heinrich; hi all owners of SiFive Unmatched + PCIe video card,
>
>Default U-Boot configuration for Unmatched always fails to initialize
>BAR0 of my video card (NVidia GT710), because the PCI driver selects the MEMORY
>region at 0x70000000 for bus_start/phys_start ("region 2", according to
>decode_regions() output), which has the size of 0x1000000. Naturally, the
>video card's BAR0 doesn't fit into this small region, because its size
>is also 0x1000000:
>
>  pci_auto_config_devices: start
>  PCI Autoconfig: Bus Memory region: [70000000-70ffffff],
>                  Physical Memory [70000000-70ffffff]
>  PCI Autoconfig: Bus Prefetchable Mem region: [2000000000-3fffffffff],
>                  Physical Memory [2000000000-3fffffffff]
>  PCI Autoconfig: Bus I/O region: [60080000-6008ffff],
>                  Physical Memory [60080000-6008ffff]
>  .......
>  pci_auto_config_devices: device pci_7:0.0
>  PCI Autoconfig: BAR 0, Mem, size=0x1000000, bus_lower=0x70400000, bus_start=0x70000000, phys_start=0x70000000
>  addr = 0x71000000
>  No room in resource, avail start=70400000 / size=1000000, need=1000000
>  PCI: Failed autoconfig bar 10
>
>The situation changes drastically if CONFIG_PCI_REGION_MULTI_ENTRY is set to "yes".
>After this, PCI starts to use "region 1" for MEMORY, which has the size of
>0xFF70000, and is, obviously, suitable for GPU's BAR0:
>
>pci_uclass_pre_probe, bus=-1/pcie at e00000000, parent=soc
>decode_regions: len=28, cells_per_record=7
>decode_regions: region 0, pci_addr=60080000, addr=60080000, size=10000, space_code=1
> - type=1, pos=0
>decode_regions: region 1, pci_addr=60090000, addr=60090000, size=ff70000, space_code=2
> - type=0, pos=1
>decode_regions: region 2, pci_addr=70000000, addr=70000000, size=1000000, space_code=2
> - type=0, pos=2
>decode_regions: region 3, pci_addr=2000000000, addr=2000000000, size=2000000000, space_code=3
> - type=8, pos=3
>....
>PCIE-0: Link up (Gen1-x8, Bus0)
>pci_uclass_post_probe: probing bus 0
>pci_bind_bus_devices: bus 0/pcie at e00000000: found device 0, function 0: find ret=-19
>pci_find_and_bind_driver: Searching for driver: vendor=f15e, device=0
>pci_find_and_bind_driver: No match found: bound generic driver instead
>pci_auto_config_devices: start
>PCI Autoconfig: Bus Memory region: [60090000-6fffffff],
>                Physical Memory [60090000-6fffffff]
>PCI Autoconfig: Bus Prefetchable Mem region: [2000000000-3fffffffff],
>                Physical Memory [2000000000-3fffffffff]
>PCI Autoconfig: Bus I/O region: [60080000-6008ffff],
>                Physical Memory [60080000-6008ffff]
>
>This picture is in full accord with Linux kernel, which also uses
>0x69000000 ("region 1") for bus_start and phys_start.
>
>With this setting, all BARs on all devices are initialized correctly,
>and, moreover, I can access memory-mapped VGA ports of the card (see [1] for
>details), which is essential for initializing the card in text mode with
>bios_emulator:
>
>PCI Autoconfig: BAR 0, Mem, size=0x1000000, bus_lower=0x60500000, bus_start=0x60090000, phys_start=0x60090000
>address=0x61000000 bus_lower=0x62000000
>
>PCI Autoconfig: BAR 1, Prf64, size=0x8000000, bus_lower=0x2000000000, bus_start=0x2000000000, phys_start=0x2000000000
>address=0x2000000000 bus_lower=0x2008000000
>
>PCI Autoconfig: BAR 2, Prf64, size=0x2000000, bus_lower=0x2008000000, bus_start=0x2000000000, phys_start=0x2000000000
>address=0x2008000000 bus_lower=0x200a000000
>
>PCI Autoconfig: BAR 3, I/O, size=0x80, bus_lower=0x60080000, bus_start=0x60080000, phys_start=0x60080000
>address=0x60080000 bus_lower=0x60080080
>
>PCI Autoconfig: ROM, size=0x80000, bus_lower=0x62000000, bus_start=0x60090000, phys_start=0x60090000
>address=0x62000000 bus_lower=0x62080000
>
>Notes:
>
>[1]: https://envytools.readthedocs.io/en/latest/hw/mmio.html#gf100-mmio-map
>

Hello Yuri,

Thank you for sharing your investigation results. Could you, please, send a patch?

Were you able to show output on HDMI?

Best regards

Heinrich