Hi wpceswpces
Are you using Coe camera? It’s mgbe might be in contention with mgbe*_0.
In case this might be helpful, it is where this comes from.
[2026-01-26 10:00:57] [ 16.547627] CPU:0, Error: top-cbb-fabric@0x8100800000, irq=16
[2026-01-26 10:00:57] [ 16.547642] **************************************
[2026-01-26 10:00:57] [ 16.547654] CPU:0, Error:top-cbb-fabric, Errmon:1
[2026-01-26 10:00:57] [ 16.549042] Error Code: PWRDOWN_ERR
[2026-01-26 10:00:57] [ 16.552881] Overflow: Multiple PWRDOWN_ERR
[2026-01-26 10:00:57] [ 16.552886]
[ 16.552887] Error Code: PWRDOWN_ERR
[ 16.552889] MASTER_ID: CCPLEX
[2026-01-26 10:00:57] [ 16.566160] Address: 0xa808ade008
[2026-01-26 10:00:57] [ 16.569996] Cache: 0x1 -- Bufferable
[2026-01-26 10:00:57] [ 16.574187] Protection: 0x2 -- Unprivileged, Non-Secure, Data Access
[2026-01-26 10:00:57] [ 16.580823] Access_Type: Read
[2026-01-26 10:00:57] [ 16.584314] Access_ID: 0x3
[2026-01-26 10:00:57] [ 16.584316] Fabric_Id: 0x4
[2026-01-26 10:00:57] [ 16.590601] Fabric: uphy0-cbb-fabric
[ 16.594444] or Fabric: aon-fabric
jp7/Linux_for_Tegra/source/kernel/kernel-noble/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra234-cbb.yaml
The Control Backbone (CBB) is comprised of the physical path from an
initiator to a target's register configuration space. CBB 2.0 consists
of multiple sub-blocks connected to each other to create a topology.
The Tegra234 SoC has different fabrics based on CBB 2.0 architecture
which include cluster fabrics BPMP, AON, PSC, SCE, RCE, DCE, FSI and
"CBB central fabric".
In CBB 2.0, each initiator which can issue transactions connects to a
Root Master Node (MN) before it connects to any other element of the
fabric. Each Root MN contains a Error Monitor (EM) which detects and
logs error. Interrupts from various EM blocks are collated by Error
Notifier (EN) which is per fabric and presents a single interrupt from
fabric to the SoC interrupt controller.
The driver handles errors from CBB due to illegal register accesses
and prints debug information about failed transaction on receiving
the interrupt from EN. Debug information includes Error Code, Error
Description, MasterID, Fabric, SlaveID, Address, Cache, Protection,
Security Group etc on receiving error notification.
If the Error Response Disable (ERD) is set/enabled for an initiator,
then SError or Data abort exception error response is masked and an
interrupt is used for reporting errors due to illegal accesses from
that initiator. The value returned on read failures is '0xFFFFFFFF'
for compatibility with PCIE.
jp7/Linux_for_Tegra/source/kernel/kernel-noble/drivers/soc/tegra/cbb/tegra234-cbb.c
/*
* In T264, AON Fabric ID value is incorrectly same as UPHY0 fabric ID.
* For 'ID = 0x4', we must check for the address which caused the error
* to find the correct fabric which returned error.
*/
tegra_cbb_print_err(file, "\t or Fabric\t\t: %s\n",
cbb->fabric->fab_list[T264_AON_FABRIC_ID].name);
tegra_cbb_print_err(file, "\t Please use Address to determine correct fabric.\n");
static const struct tegra234_fabric_lookup tegra241_cbb_fab_list[];
/*
* Possible causes for Slave and Timeout errors.
* SLAVE_ERR:
* Slave being accessed responded with an error. Slave could return
* an error for various cases :
* Unsupported access, clamp setting when power gated, register
* level firewall(SCR), address hole within the slave, etc
*
* TIMEOUT_ERR:
* No response returned by slave. Can be due to slave being clock
* gated, under reset, powered down or slave inability to respond
* for an internal slave issue
*/
static const struct tegra_cbb_error tegra241_cbb_errors[] = { .code = "PWRDOWN_ERR",
.desc = "Attempt to access a portion of fabric that is powered down"
Here’s dts
source/hardware/nvidia/t264/nv-public/tegra264.dtsi
bus@0 {
compatible = "simple-bus";
...
top0-cbb-fabric@8100800000 {
compatible = "nvidia,tegra264-top0-cbb-fabric";
reg = <0x81 0x800000 0x0 0x800000>;
interrupts = <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>;
status = "disabled";
};
vision-cbb-fabric@8180800000 {
compatible = "nvidia,tegra264-vision-cbb-fabric";
reg = <0x81 0x80800000 0x0 0x800000>;
interrupts = <GIC_SPI 324 IRQ_TYPE_LEVEL_HIGH>;
status = "disabled";
};
source/hardware/nvidia/t264/nv-public/nv-platform/tegra264-p3834-common.dtsi
/ {
bus@0 {
top0-cbb-fabric@8100800000 {
status = "okay";
};
Is your top0-cbb-fabric@8100800000 “okay” ?
node=/sys/firmware/devicetree/base/bus@0/top0-cbb-fabric@8100800000
tr '\0' '\n' < $node/compatible
tr '\0' '\n' < $node/name
tr '\0' '\n' < $node/status
hexdump -Cv $node/reg
hexdump -Cv $node/interrupts