On 11/4/19 9:09 AM, Stefan Wahren wrote:
[snip]
>> + reserved-memory {
>> + #address-cells = <2>;
>> + #size-cells = <1>;
>> + ranges;
>> +
>> + /*
>> + * arm64 reserves the CMA by default somewhere in ZONE_DMA32,
>> + * that's not good enough for the Raspberry Pi 4 as some
>> + * devices can only address the lower 1G of memory (ZONE_DMA).
>> + */
>> + linux,cma {
>> + compatible = "shared-dma-pool";
>> + size = <0x2000000>; /* 32MB */
>> + alloc-ranges = <0x0 0x00000000 0x40000000>;
>> + reusable;
>> + linux,cma-default;
>> + };
>> + };
>> +
>
> i think this is a SoC-specific issue not a board specifc one. Please
> move this to bcm2711.dtsi
This sounds like a possibly fragile solution if someone changes
CONFIG_CMA_SIZE_MBYTES to a value greater than 32MB no?
I know we don't want machine descriptors for ARM64 kernels, but since
there is already a specific 2711 machine compatible string check, maybe
you could use that as well for determining whether arm64_dma_phys_limit
or arm64_dma32_phys_limit should be chosen?
--
Florian
