On 12/12/17 18:02, Alexandre Torgue wrote:
> On cortex-M7 MCU, DMA have to use a non cache-able memory area. For this
> reason a dedicated memory pool is created for DMA.
> This patch creates a DMA memory pool of 1MB of each STM32 MCU which
> embeds a cortex-M7 expect stm32f746-disco. Indeed, as stm32f746-disco has
^^^^^^
except?
> only a 8MB SDRAM and it's tricky to reduce memory used by Kernel.
I guess that 1MB is a kind of "should be enough" estimate, probably something
along with [1] would give you exact numbers...
>
> Signed-off-by: Alexandre Torgue <alexandre.torgue@xxxxxx>
>
> diff --git a/arch/arm/boot/dts/stm32746g-eval.dts b/arch/arm/boot/dts/stm32746g-eval.dts
> index 2d4e717..3f52a7b 100644
> --- a/arch/arm/boot/dts/stm32746g-eval.dts
> +++ b/arch/arm/boot/dts/stm32746g-eval.dts
> @@ -57,6 +57,19 @@
> reg = <0xc0000000 0x2000000>;
> };
>
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + linux,dma {
> + compatible = "shared-dma-pool";
> + linux,dma-default;
> + no-map;
> + reg = <0xc1f00000 0x100000>;
> + };
> + };
> +
> aliases {
> serial0 = &usart1;
> };
> diff --git a/arch/arm/boot/dts/stm32f769-disco.dts b/arch/arm/boot/dts/stm32f769-disco.dts
> index 4463ca1..08699a2 100644
> --- a/arch/arm/boot/dts/stm32f769-disco.dts
> +++ b/arch/arm/boot/dts/stm32f769-disco.dts
> @@ -57,6 +57,19 @@
> reg = <0xC0000000 0x1000000>;
> };
>
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + linux,dma {
> + compatible = "shared-dma-pool";
> + linux,dma-default;
> + no-map;
> + reg = <0xc0f00000 0x100000>;
> + };
> + };
> +
> aliases {
> serial0 = &usart1;
> };
> diff --git a/arch/arm/boot/dts/stm32h743i-disco.dts b/arch/arm/boot/dts/stm32h743i-disco.dts
> index 79e841d..104545a 100644
> --- a/arch/arm/boot/dts/stm32h743i-disco.dts
> +++ b/arch/arm/boot/dts/stm32h743i-disco.dts
> @@ -57,6 +57,19 @@
> reg = <0xd0000000 0x2000000>;
> };
>
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + linux,dma {
> + compatible = "shared-dma-pool";
> + linux,dma-default;
> + no-map;
> + reg = <0xc1f00000 0x100000>;
> + };
> + };
> +
> aliases {
> serial0 = &usart2;
> };
> diff --git a/arch/arm/boot/dts/stm32h743i-eval.dts b/arch/arm/boot/dts/stm32h743i-eval.dts
> index 9f0e72c..5bd4b16 100644
> --- a/arch/arm/boot/dts/stm32h743i-eval.dts
> +++ b/arch/arm/boot/dts/stm32h743i-eval.dts
> @@ -57,6 +57,19 @@
> reg = <0xd0000000 0x2000000>;
> };
>
> + reserved-memory {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + linux,dma {
> + compatible = "shared-dma-pool";
> + linux,dma-default;
> + no-map;
> + reg = <0xc1f00000 0x100000>;
> + };
> + };
> +
> aliases {
> serial0 = &usart1;
> };
>
Usage of dma-default looks correct to me, so FWIW
Reviewed-by: Vladimir Murzin <vladimir.murzin@xxxxxxx>
[1] https://lkml.org/lkml/2017/7/7/296
Vladimir
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