Re: [PATCH 1/2] ARM: dts: stm32: Setup 4M bytes reserved memory for mmap

[dillon min]

Hi Christoph Hellwig,

This is the patchset. for your reference.

thanks,

On Mon, Jun 8, 2020 at 4:30 PM <dillon.minfei@xxxxxxxxx> wrote:
>
> From: dillon min <dillon.minfei@xxxxxxxxx>
>
> To mmap a framebuffer or v4l2 buffer from kernel to userspace on
> no-mmu platform, we need rely on 'arm_nommu_dma_ops' from
> arch/arm/mm/dma-mapping-nommu.c , so setup 4M bytes memory
> reserved for this purpose.
>
> Signed-off-by: dillon min <dillon.minfei@xxxxxxxxx>
> ---
>  arch/arm/boot/dts/stm32f469-disco.dts | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/arch/arm/boot/dts/stm32f469-disco.dts b/arch/arm/boot/dts/stm32f469-disco.dts
> index 9397db0c43de..082b24ee81f7 100644
> --- a/arch/arm/boot/dts/stm32f469-disco.dts
> +++ b/arch/arm/boot/dts/stm32f469-disco.dts
> @@ -65,6 +65,20 @@
>                 reg = <0x00000000 0x1000000>;
>         };
>
> +       reserved-memory {
> +               #address-cells = <1>;
> +               #size-cells = <1>;
> +               ranges;
> +
> +               linux,dma {
> +                       compatible = "shared-dma-pool";
> +                       size = <0x400000>;
> +                       no-map;
> +                       linux,dma-default;
> +               };
> +
> +       };
> +
>         aliases {
>                 serial0 = &usart3;
>         };
> --
> 2.7.4
>