Re: [PATCH 2/3] riscv: dts: spacemit: Move UARTs under dma-bus for K1

[Vivian Wang]

On 6/24/25 20:21, Guodong Xu wrote:
> On Mon, Jun 23, 2025 at 6:04 PM Vivian Wang <wangruikang@xxxxxxxxxxx> wrote:
> > UART devices in Spacemit K1 use dma-bus DMA translations. Move these
> > nodes under dma-bus to reflect this fact.
...
> > -               sec_uart1: serial@f0612000 {
> > -                       compatible = "spacemit,k1-uart", "intel,xscale-uart";
> > -                       reg = <0x0 0xf0612000 0x0 0x100>;
> > -                       interrupts = <43>;
> > -                       clock-frequency = <14857000>;
> > -                       reg-shift = <2>;
> > -                       reg-io-width = <4>;
> > -                       status = "reserved"; /* for TEE usage */
> > -               };
> > -
> Are you sure sec_uart1 should be placed under the dma_bus? Please double
> check. If sec_uart1 and other peripherals supported by the secure DMA
> (base address: 0xF0600000) share the same address mapping as dma_bus, and
> if they can be accessed by the linux kernel in some cases (as saying
> 'reserved'), then that makes sense. If not, better not move them.

Bianbu's DT from SpacemiT [1] shows sec_uart1 using dram_range4, and it 
made sense to me. However just to be sure I will ask SpacemiT for 
confirmation.

Vivian "dramforever" Wang

[1]: https://gitee.com/bianbu-linux/linux-6.6/blob/k1-bl-v2.2.y/arch/riscv/boot/dts/spacemit/k1-x.dtsi

> --
> Guodong