Re: [PATCH] dma-pool: use single atomic pool for both DMA zones

[Nicolas Saenz Julienne]

Hi Jim,

On Tue, 2020-07-07 at 17:08 -0500, Jeremy Linton wrote:
> Hi,
> 
> I spun this up on my 8G model using the PFTF firmware from:
> 
> https://github.com/pftf/RPi4/releases
> 
> Which allows me to switch between ACPI/DT on the machine. In DT mode it 
> works fine now, 

Nice, would that count as a Tested-by from you?

> but with ACPI I continue to have failures unless I 
> disable CMA via cma=0 on the kernel command line. 

Yes, I see why, in atomic_pool_expand() memory is allocated from CMA without
checking its correctness. That calls for a separate fix. I'll try to think of
something.

> It think that is because
> 
> using DT:
> 
> [    0.000000] Reserved memory: created CMA memory pool at
> 0x0000000037400000, size 64 MiB
> 
> 
> using ACPI:
> [    0.000000] cma: Reserved 64 MiB at 0x00000000f8000000
> 
> Which is AFAIK because the default arm64 CMA allocation is just below 
> the arm64_dma32_phys_limit.

As I'm sure you know, we fix the CMA address trough DT, isn't that possible
trough ACPI?

Regards,
Nicolas

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