PowerMac7,3 DualG5 with [AMD/ATI] RV360 [Radeon 9600/X1050 Series] GPU not loading firmware...

Wondering if there are any ideas on how to approach the mystery of the R300_cp.bin firmware that will not load:

[    2.627772] radeon 0000:f0:10.0: firmware: failed to load radeon/R300_cp.bin (-2)
[    2.627802] radeon 0000:f0:10.0: Direct firmware load for radeon/R300_cp.bin failed with error -2
[    2.627810] [drm:.r100_cp_init [radeon]] *ERROR* Failed to load firmware!
[    2.628128] radeon 0000:f0:10.0: failed initializing CP (-2).

I recently set up this DualG5 with Debian 11 Sid.

/$ cat /proc/cpuinfo
processor    : 0
cpu        : PPC970FX, altivec supported
clock        : 2000.000000MHz
revision    : 3.0 (pvr 003c 0300)

processor    : 1
cpu        : PPC970FX, altivec supported
clock        : 2000.000000MHz
revision    : 3.0 (pvr 003c 0300)

timebase    : 33333333
platform    : PowerMac
model        : PowerMac7,3
machine        : PowerMac7,3
motherboard    : PowerMac7,3 MacRISC4 Power Macintosh
detected as    : 336 (PowerMac G5)
pmac flags    : 00000000
L2 cache    : 512K unified
pmac-generation    : NewWorld

---

/$ lspci
0000:f0:0b.0 Host bridge: Apple Inc. U3H AGP Bridge
0000:f0:10.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV360 [Radeon 9600/X1050 Series]
0001:00:00.0 Host bridge: Apple Inc. U3 HT Bridge
0001:00:01.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] AMD-8131 PCI-X Bridge (rev 12)
0001:00:02.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] AMD-8131 PCI-X Bridge (rev 12)
0001:00:03.0 PCI bridge: Apple Inc. K2 HT-PCI Bridge
0001:00:04.0 PCI bridge: Apple Inc. K2 HT-PCI Bridge
0001:00:05.0 PCI bridge: Apple Inc. K2 HT-PCI Bridge
0001:00:06.0 PCI bridge: Apple Inc. K2 HT-PCI Bridge
0001:00:07.0 PCI bridge: Apple Inc. K2 HT-PCI Bridge
0001:01:07.0 Unassigned class [ff00]: Apple Inc. K2 KeyLargo Mac/IO (rev 60)
0001:01:08.0 USB controller: Apple Inc. K2 KeyLargo USB
0001:01:09.0 USB controller: Apple Inc. K2 KeyLargo USB
0001:02:0b.0 USB controller: NEC Corporation OHCI USB Controller (rev 43)
0001:02:0b.1 USB controller: NEC Corporation OHCI USB Controller (rev 43)
0001:02:0b.2 USB controller: NEC Corporation uPD72010x USB 2.0 Controller (rev 04)
0001:03:0d.0 Unassigned class [ff00]: Apple Inc. K2 ATA/100
0001:03:0e.0 FireWire (IEEE 1394): Apple Inc. K2 FireWire
0001:04:0f.0 Ethernet controller: Apple Inc. K2 GMAC (Sun GEM)
0001:05:0c.0 IDE interface: Broadcom K2 SATA

---

I have installed the correct firmware packages I believe:

$ apt list | grep installed | grep firmware

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

firmware-amd-graphics/unstable,now 20210818-1 all [installed]
firmware-linux-free/unstable,now 20200122-1 all [installed,automatic]
firmware-linux-nonfree/unstable,now 20210818-1 all [installed]
firmware-misc-nonfree/unstable,now 20210818-1 all [installed,automatic]

---

and the firmware seems to be there:

$ ls -la /lib/firmware/radeon/R3*
-rw-r--r-- 1 root root 2048 Aug 24 08:46 /lib/firmware/radeon/R300_cp.bin

---------------

and yet I see this:

$ sudo dmesg | grep radeon
[    2.532448] [drm] radeon kernel modesetting enabled.
[    2.532582] fb0: switching to radeondrmfb from OFfb ATY,Whelk_
[    2.533770] fb1: switching to radeondrmfb from OFfb ATY,Whelk_
[    2.534038] radeon 0000:f0:10.0: vgaarb: deactivate vga console
[    2.534814] radeon 0000:f0:10.0: enabling device (0006 -> 0007)
[    2.536513] radeon 0000:f0:10.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0x0000
[    2.624118] radeon 0000:f0:10.0: VRAM: 256M 0x00000000A0000000 - 0x00000000AFFFFFFF (128M used)
[    2.624128] radeon 0000:f0:10.0: GTT: 512M 0x0000000080000000 - 0x000000009FFFFFFF
[    2.624213] radeon 0000:f0:10.0: dma_iommu_get_required_mask: returning bypass mask 0x1ffffffff
[    2.624413] [drm] radeon: 128M of VRAM memory ready
[    2.624419] [drm] radeon: 512M of GTT memory ready.
[    2.627065] [drm] radeon: 1 quad pipes, 1 Z pipes initialized
[    2.627199] radeon 0000:f0:10.0: WB enabled
[    2.627210] radeon 0000:f0:10.0: fence driver on ring 0 use gpu addr 0x0000000080000000
[    2.627644] [drm] radeon: irq initialized.
[    2.627772] radeon 0000:f0:10.0: firmware: failed to load radeon/R300_cp.bin (-2)
[    2.627802] radeon 0000:f0:10.0: Direct firmware load for radeon/R300_cp.bin failed with error -2
[    2.627810] [drm:.r100_cp_init [radeon]] *ERROR* Failed to load firmware!
[    2.628128] radeon 0000:f0:10.0: failed initializing CP (-2).
[    2.628145] radeon 0000:f0:10.0: Disabling GPU acceleration
[    2.628158] [drm] radeon: cp finalized
[    2.794433] radeon 0000:f0:10.0: [drm] fb0: radeon frame buffer device
[    2.810380] [drm] Initialized radeon 2.50.0 20080528 for 0000:f0:10.0 on minor 0

I tried forcing a reinstall of: firmware-amd-graphics

but that seems to have made no difference.

thanks to all!

Ken