Re: [PATCH 9/9] arm64: dts: imx95: Describe Mali G310 GPU

Marek Vasut
2025-02-28T18:27:29Z

On 2/28/25 11:39 AM, Alexander Stein wrote:
> Am Donnerstag, 27. Februar 2025, 23:21:22 CET schrieb Frank Li:
>> On Thu, Feb 27, 2025 at 10:34:20PM +0100, Marek Vasut wrote:
>>> On 2/27/25 10:27 PM, Frank Li wrote:
>>>
>>> [...]
>>>
>>>>>>> + gpu: gpu@4d900000 {
>>>>>>> + compatible = "fsl,imx95-mali", "arm,mali-valhall-csf";
>>>>>>> + reg = <0 0x4d900000 0 0x480000>;
>>>>>>> + clocks = <&scmi_clk IMX95_CLK_GPU>;
>>>>>>> + clock-names = "core";
>>>>>>> + interrupts = <GIC_SPI 288 IRQ_TYPE_LEVEL_HIGH>,
>>>>>>> + <GIC_SPI 289 IRQ_TYPE_LEVEL_HIGH>,
>>>>>>> + <GIC_SPI 290 IRQ_TYPE_LEVEL_HIGH>;
>>>>>>> + interrupt-names = "gpu", "job", "mmu";
>>>>>>> + mali-supply = <&gpu_fixed_reg>;
>>>>>>> + operating-points-v2 = <&gpu_opp_table>;
>>>>>>> + power-domains = <&scmi_devpd IMX95_PD_GPU>, <&scmi_perf IMX95_PERF_GPU>;
>>>>>>> + power-domain-names = "mix", "perf";
>>>>>>> + resets = <&gpu_blk_ctrl 0>;
>>>>>>> + #cooling-cells = <2>;
>>>>>>> + dynamic-power-coefficient = <1013>;
>>>>>>> + status = "disabled";
>>>>>>
>>>>>> GPU is internal module, which have not much dependence with other module
>>>>>> such as pinmux. why not default status is "disabled". Supposed gpu driver
>>>>>> will turn off clock and power if not used.
>>>>> My thinking was that there are MX95 SoC with GPU fused off, hence it is
>>>>> better to keep the GPU disabled in DT by default. But I can also keep it
>>>>> enabled and the few boards which do not have MX95 SoC with GPU can
>>>>> explicitly disable it in board DT.
>>>>>
>>>>> What do you think ?
>>>>
>>>> GPU Fuse off should use access-control, see thread
>>>> https://lore.kernel.org/imx/20250207120213.GD14860@localhost.localdomain/
>>> Did that thread ever go anywhere ? It seems there is no real conclusion, is
>>> there ? +Cc Alex .
>>
>> The direction is use access-control to indicate fuse disable. Only
>> implement detail is under discussion.
>
> Well, the discussion ended up to be more complicated for i.MX8M.

Aren't we missing the access controller in MX95 DT so far ?
And maybe some driver to match ?

> For i.MX95
> things are a bit easier, as fuses and clocks are controlled by System
> Manager (SM), accessed using SCMI. [1] is more important for imx95.
I think SCMI is replacing GPL code in kernel with stubs that call
non-free firmware, which removes flexibility and makes long term (or
any) maintenance much more complicated.