PCIE can not write by devmem2

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

xavier ac pcie rp, tda4 as a pcie ep.In xavier,devmem2 can not write the bar mem,but orin is okay.xavier sdk version is 32.7.

3

please add CONFIG_STRICT_DEVMEM=n to tegra_defconfig

4

i will test,but i think this is not the reason.it does not report error,but readback is
not right.I have write a driver and ioremap the bar memory…in the driver, I write it ,but readback is also wrong value.
///////////////////////////////////logs//////////////////////////////////////////////////////////
0005:01:00.0 Unassigned class [ff00]: Texas Instruments Device b0c0
Flags: fast devsel, IRQ 557
Memory at 1f42000000 (32-bit, non-prefetchable) [size=64K]
Memory at 1f42010000 (32-bit, non-prefetchable) [size=64K]
Memory at 1f40000000 (32-bit, non-prefetchable) [size=4M]
Memory at 1f40400000 (32-bit, non-prefetchable) [size=4M]
Memory at 1f40800000 (32-bit, non-prefetchable) [size=4M]
Memory at 1f40c00000 (32-bit, non-prefetchable) [size=4M]
Capabilities: [80] Power Management version 3
Capabilities: [90] MSI: Enable+ Count=2/2 Maskable- 64bit+
Capabilities: [b0] MSI-X: Enable- Count=2 Masked-
Capabilities: [c0] Express Endpoint, MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [140] Alternative Routing-ID Interpretation (ARI)
Capabilities: [150] Device Serial Number 00-00-00-00-00-00-00-00
Capabilities: [160] Power Budgeting <?> Capabilities: [1b8] Latency Tolerance Reporting Capabilities: [1c0] #16 Capabilities: [200] Single Root I/O Virtualization (SR-IOV) Capabilities: [300] #19 Capabilities: [400] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [440] Process Address Space ID (PASID)
Capabilities: [4c0] Virtual Channel
Capabilities: [5c0] Address Translation Service (ATS)
Capabilities: [640] Page Request Interface (PRI)
Capabilities: [900] L1 PM Substates
Capabilities: [a20] Precision Time Measurement
Kernel driver in use: pciep-soc
Kernel modules: pciep_socinter

root@localhost:/home/nvidia# devmem2 0x1f42000000 w 0x123
/dev/mem opened.
Memory mapped at address 0x7f95706000.
Value at address 0x42000000 (0x7f95706000): 0xFFFFFFFF
Written 0x123; readback 0xFFFFFFFF
root@localhost:/home/nvidia#

5

please tested with the document steps first.

https://docs.nvidia.com/jetson/archives/r35.3.1/DeveloperGuide/text/SD/Communications/PcieEndpointMode.html?highlight=endpoint

6

CONFIG_STRICT_DEVMEM is not set.
I have already tested as the steps, but bar mem also cannot write. the orin works well.

7

xavier-xavier is ok, xavier pcie-rp ----tda4 ep is not ok, orin pcie-rp------tda4 is ok. the tda4 pcie dev is added by “echo 1 >/sys/class/pci_bus/0005:00/rescan”.

8

I add num-viewport in the dts.
what dose “disabled” mean in “Memory at 1f42000000 (32-bit, non-prefetchable) [disabled] [size=64K]”
/////////////////////////////////////////////////logs/////////////////////////////////////////////////
0005:01:00.0 Unassigned class [ff00]: Texas Instruments Device b0c0
Flags: fast devsel, IRQ 255
Memory at 1f42000000 (32-bit, non-prefetchable) [disabled] [size=64K]
Memory at 1f42010000 (32-bit, non-prefetchable) [disabled] [size=64K]
Memory at 1f40000000 (32-bit, non-prefetchable) [disabled] [size=4M]
Memory at 1f40400000 (32-bit, non-prefetchable) [disabled] [size=4M]
Memory at 1f40800000 (32-bit, non-prefetchable) [disabled] [size=4M]
Memory at 1f40c00000 (32-bit, non-prefetchable) [disabled] [size=4M]
Capabilities: [80] Power Management version 3
Capabilities: [90] MSI: Enable- Count=1/2 Maskable- 64bit+
Capabilities: [b0] MSI-X: Enable- Count=2 Masked-
Capabilities: [c0] Express Endpoint, MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [140] Alternative Routing-ID Interpretation (ARI)
Capabilities: [150] Device Serial Number 00-00-00-00-00-00-00-00
Capabilities: [160] Power Budgeting <?> Capabilities: [1b8] Latency Tolerance Reporting Capabilities: [1c0] #16 Capabilities: [200] Single Root I/O Virtualization (SR-IOV) Capabilities: [300] #19 Capabilities: [400] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [440] Process Address Space ID (PASID)
Capabilities: [4c0] Virtual Channel
Capabilities: [5c0] Address Translation Service (ATS)
Capabilities: [640] Page Request Interface (PRI)
Capabilities: [900] L1 PM Substates
Capabilities: [a20] Precision Time Measurement
Kernel modules: pciep_socinter

9

It can works now, I use the way below. Why it is invalid use rescan way
cd /sys/bus/platform/drivers/tegra-pcie-dw
echo 141a0000.pcie > unbind
echo 141a0000.pcie > bind

11

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