[PATCH 2/2] rockchip: rk3399: enable spl-fifo-mode for sdmmc only when needed

[Jerome Forissier]

On 6/9/22 08:23, Jerome Forissier wrote:
> Commit 5c606ca35c42 ("rockchip: rk3399: enable spl-fifo-mode for sdmmc")
> mentions that the RK3399 SoC can't do DMA between SDMMC and SRAM.
> According to the TRM "7.3.2 Embedded SRAM access path" [1], only the
> 8KB SRAM at 0xff3b0000 (INTMEM1) is in this situation. The 192KB SRAM
> can be accessed by both DMA controllers.
> 
> Assuming the only use case for writing from MMC to INTMEM1 is loading
> a FIT image, and with the introduction of a temporary buffer for that
> purpose (CONFIG_SPL_LOAD_FIT_IMAGE_BUFFER_SIZE, which is required
> anyways to ensure the destination boundaries are enforced), then
> spl-fifo-mode is not needed anymore and DMA can be enabled safely.
> 
> Link: [1] https://www.rockchip.fr/Rockchip%20RK3399%20TRM%20V1.4%20Part1.pdf
> CC: Deepak Das <deepakdas.linux at gmail.com>
> Signed-off-by: Jerome Forissier <jerome.forissier at linaro.org>
> ---
>  arch/arm/dts/rk3399-u-boot.dtsi | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm/dts/rk3399-u-boot.dtsi b/arch/arm/dts/rk3399-u-boot.dtsi
> index 716b9a433a..a1b6d6f007 100644
> --- a/arch/arm/dts/rk3399-u-boot.dtsi
> +++ b/arch/arm/dts/rk3399-u-boot.dtsi
> @@ -124,8 +124,10 @@
>  &sdmmc {
>  	u-boot,dm-pre-reloc;
>  
> +#ifndef CONFIG_SPL_LOAD_FIT_IMAGE_BUFFER_SIZE

Oops, that should rather be:

+#if (CONFIG_SPL_LOAD_FIT_IMAGE_BUFFER_SIZE == 0)

>  	/* mmc to sram can't do dma, prevent aborts transferring TF-A parts */
>  	u-boot,spl-fifo-mode;
> +#endif
>  };
>  
>  &spi1 {