[PATCH v11 07/11] device-mapping: Introduce DMA range map, supplanting dma_pfn_offset

Florian Fainelli f.fainelli at gmail.com
Thu Sep 3 00:36:29 UTC 2020

On 9/2/2020 3:38 PM, Nathan Chancellor wrote:
>> Hello Nathan,
>> Can you tell me how much memory your RPI has and if all of it is
> This is the 4GB version.
>> accessible by the PCIe device?  Could you also please include the DTS
>> of the PCIe node?  IIRC, the RPI firmware does some mangling of the
>> PCIe DT before Linux boots -- could you describe what is going on
>> there?
> Unfortunately, I am not familiar with how to get this information. If
> you could provide some instructions for how to do so, I am more than
> happy to. I am not very knowleagable about the inner working of the Pi,
> I mainly use it as a test platform for making sure that LLVM does not
> cause problems on real devices.

Can you bring the dtc application to your Pi root filesystem, and if so, 
can you run the following:

dtc -I fs -O dtb /proc/device-tree -f > /tmp/device.dtb

or cat /sys/firmware/fdt > device.dtb

and attach the resulting file?

>> Finally, can you attach the text of the full boot log?
> I have attached a working and broken boot log. Thank you for the quick
> response!

Is it possible for you to rebuild your kernel with CONFIG_MMC_DEBUG by 
any chance?

I have a suspicion that this part of the DTS for the bcm2711.dtsi 
platform is at fault:


and the resulting dma-ranges parsing is just not working for reasons to 
be determined.

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