Re: [PATCH v2] arm64: dts: qcom: sc8280xp: Define CMA region for CRD and X13s

[Johan Hovold <johan@kernel.org>]

On Tue, Jan 17, 2023 at 10:46:30AM -0800, Bjorn Andersson wrote:
> While booting the CRD, a series of CMA allocation errors can be seen in
> the kernel log:
> 
>   cma: cma_alloc: reserved: alloc failed, req-size: 128 pages, ret: -12
> 
> Growing the CMA region and querying /proc/meminfo indicates that a newly
> booted system (currently) uses 64MB CMA.

The NVMe driver buffers alone always take up 64 MB and in total roughly
92 MB is used on the CRD after boot here. Perhaps you're missing some
driver in you config (e.g. modem or wifi?).

On the X13s I even have 105 MB allocated after boot.

That's why I increased the CMA region to 128 MB in my out-of-tree
config, which is also what you are doing here but in the devicetree.

> Define a memory region sufficiently large for the current use cases, to
> avoid forcing users to add this themselves, through command line
> parameters etc.
> 
> While fixing the CRD define the same region for the X13s.
> 
> Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
> ---
> 
> Changes since v1:
> - Updated commit message

> +
> +	reserved-memory {
> +		linux,cma {
> +			compatible = "shared-dma-pool";
> +			size = <0x0 0x8000000>;
> +			reusable;
> +			linux,cma-default;
> +		};
> +	};
>  };

Johan