[PATCH v3 7/8] riscv: dts: thead: th1520: Add IMG BXM-4-64 GPU node

[Ulf Hansson]

On Wed, 4 Jun 2025 at 18:48, Matt Coster <Matt.Coster at imgtec.com> wrote:
>
> On 03/06/2025 13:27, Ulf Hansson wrote:
> > On Fri, 30 May 2025 at 00:24, Michal Wilczynski
> > <m.wilczynski at samsung.com> wrote:
> >>
> >> Add a device tree node for the IMG BXM-4-64 GPU present in the T-HEAD
> >> TH1520 SoC used by the Lichee Pi 4A board. This node enables support for
> >> the GPU using the drm/imagination driver.
> >>
> >> By adding this node, the kernel can recognize and initialize the GPU,
> >> providing graphics acceleration capabilities on the Lichee Pi 4A and
> >> other boards based on the TH1520 SoC.
> >>
> >> Add fixed clock gpu_mem_clk, as the MEM clock on the T-HEAD SoC can't be
> >> controlled programatically.
> >>
> >> Signed-off-by: Michal Wilczynski <m.wilczynski at samsung.com>
> >> ---
> >>  arch/riscv/boot/dts/thead/th1520.dtsi | 22 ++++++++++++++++++++++
> >>  1 file changed, 22 insertions(+)
> >>
> >> diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
> >> index 6170eec79e919b606a2046ac8f52db07e47ef441..ee937bbdb7c08439a70306f035b1cc82ddb4bae2 100644
> >> --- a/arch/riscv/boot/dts/thead/th1520.dtsi
> >> +++ b/arch/riscv/boot/dts/thead/th1520.dtsi
> >> @@ -225,6 +225,13 @@ aonsys_clk: clock-73728000 {
> >>                 #clock-cells = <0>;
> >>         };
> >>
> >> +       gpu_mem_clk: mem-clk {
> >> +               compatible = "fixed-clock";
> >> +               clock-frequency = <0>;
> >> +               clock-output-names = "gpu_mem_clk";
> >> +               #clock-cells = <0>;
> >> +       };
> >> +
> >>         stmmac_axi_config: stmmac-axi-config {
> >>                 snps,wr_osr_lmt = <15>;
> >>                 snps,rd_osr_lmt = <15>;
> >> @@ -504,6 +511,21 @@ clk: clock-controller at ffef010000 {
> >>                         #clock-cells = <1>;
> >>                 };
> >>
> >> +               gpu: gpu at ffef400000 {
> >> +                       compatible = "thead,th1520-gpu", "img,img-bxm-4-64",
> >> +                                    "img,img-rogue";
> >> +                       reg = <0xff 0xef400000 0x0 0x100000>;
> >> +                       interrupt-parent = <&plic>;
> >> +                       interrupts = <102 IRQ_TYPE_LEVEL_HIGH>;
> >> +                       clocks = <&clk_vo CLK_GPU_CORE>,
> >> +                                <&gpu_mem_clk>,
> >> +                                <&clk_vo CLK_GPU_CFG_ACLK>;
> >> +                       clock-names = "core", "mem", "sys";
> >> +                       power-domains = <&aon TH1520_GPU_PD>;
> >> +                       power-domain-names = "a";
> >
> > If the power-domain-names are really needed, please pick a
> > useful/descriptive name.
>
> This isn't the first time our unfortunate power domain names have come
> up [1][2]. Sadly, we're stuck with them for Rogue.

Wow, that's really crazy.

BTW, are there any reasons why you can't rely on attaching them by
index instead, via dev_pm_domain_attach_by_id() for example? Thus
entirely drop the names in the DT docs?

It sounds like the names don't really have a meaning, or do they?

>
> Matt
>
> [1]: https://lore.kernel.org/r/ff4e96e4-ebc2-4c50-9715-82ba3d7b8612@imgtec.com/
> [2]: https://lore.kernel.org/r/cc6a19b3-ba35-465c-9fa6-a764df7c01c1@imgtec.com/
>
> >

[...]

Kind regards
Uffe