Re: [PATCH v2 4/4] arm64: dts: qcom: x1-dell-thena: bump linux,cma to 256 MiB

[Bryan O'Donoghue]

On 22/05/2026 18:16, Michael Scott wrote:
> > └─[$] <git:(0.7.0-multipass-v0*)>
>
> Good point about the libcamera version. I debugged this on Ubuntu 26.04 
> (v0.7.0+patches). I tried testing v0.7.1, but it caused a crash due to 
> API changes with other parts of the subsystem.  I checked the diff of 
> upstream between v0.7.0 and v0.7.1 for the dma allocator code and I 
> didn't see any changes, but I wasn't looking at the software ISP changes.
>
> This highlights that "I'm doing this wrong". I'll move to a cleaner 
> rolling distro where staying current is a lot easier.
>
> The GPUISP support looks great!
>
> Dropping this patch as I'm not understanding the full allocator story. 
> Sorry for the noise.

The whole make CMA bigger thing is an error I was pushing myself.

CMA is required for some systems like say Hantro on i.MX where - the 
encoder doesn't know how to deal with non PHYS contig memory so when you 
are passing framebuffers around from once hw block to another, you need 
to make them physically contiguous.

Not a problem for us on Qcom hw though. Like Rob said, I'm actually not 
sure why we need a CMA block on Qcom hardware at all.

GPU or WiFi I think but not for Camera anymore anyway.

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bod