Re: [PATCH v2] accel/rocket: request the core clocks by name

[Sebastian Reichel]

Hi,

On Wed, Jul 29, 2026 at 03:07:43PM +0200, Igor Paunovic wrote:
> rocket_core_init() hands core->clks to devm_clk_bulk_get() without ever
> setting the .id members. The rocket_core array is allocated with
> devm_kcalloc() in rocket_device_init(), and rocket_probe() only fills in
> .rdev, .dev and .index, so all four clk_bulk_data entries are requested
> with a NULL con_id (unlike core->resets, whose ids are set a few lines
> above).
> 
> clk_get(dev, NULL) ends up in of_clk_get_hw(np, 0, NULL), and
> of_parse_clkspec() only consults "clock-names" when a name was passed,
> so the index stays 0 for all four entries. Every entry therefore ends up
> holding a handle to the *first* clock of the DT "clocks" property, i.e.
> ACLK_NPUn. Nothing fails: probe succeeds and the driver believes it owns
> four different clocks.
> 
> The consequence is that rocket_device_runtime_resume() prepares and
> enables the AXI clock four times, while hclk, pclk and - most
> importantly - the NPU compute clock ("npu", SCMI_CLK_NPU on RK3588) are
> never prepared or enabled by this driver at all. The NPU still works
> only because the Rockchip power-domain driver sets GENPD_FLAG_PM_CLK and
> its attach_dev() callback walks the device node with of_clk_get() and
> adds every clock to the pm_clk list, so genpd happens to keep the
> remaining clocks running. The bug is therefore latent today, but it
> means the driver holds no reference to the clock that actually feeds the
> NPU, which stands in the way of any future frequency scaling
> (OPP/devfreq) work.
> 
> Found on an Orange Pi 5 Plus (RK3588) by reading the live clock tree:
> /sys/kernel/debug/clk/clk_summary shows four "fdab0000.npu" consumer
> handles on aclk_npu0 (and likewise on aclk_npu1/aclk_npu2 for the other
> two cores), while hclk_npu0, pclk_npu_root and scmi_clk_npu have no
> "fdab0000.npu" consumer at all - their only consumers are the
> "npu@fdab0000" handles created by the power-domain driver via
> of_clk_get().
> 
> Set the ids explicitly, in the order mandated by the binding
> (Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml):
> aclk, hclk, npu, pclk. After the change the driver holds one handle per
> distinct clock and clk_bulk_prepare_enable() covers all four.
> 
> Note that this is a user-visible tightening for out-of-tree DTs: the
> old NULL-id requests resolved by index and succeeded no matter what
> "clock-names" contained, while the named requests fail probe with
> -ENOENT when one of the four names is missing. That is the right
> outcome for in-tree users - the binding requires exactly these four
> clock-names and rk3588-base.dtsi carries them on all three cores - but
> a DT that relied on the permissive lookup goes from silently running on
> the wrong clock handles to not probing at all, so record the change
> here where git log will find it.
> 
> Fixes: ed98261b4168 ("accel/rocket: Add a new driver for Rockchip's NPU")
> Signed-off-by: Igor Paunovic <royalnet026@xxxxxxxxx>
> Reviewed-by: Jiaxing Hu <gahing@xxxxxxxxxxxxx>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>

-- Sebastian

> v2:
>  - document that resolving by name is a behaviour change for DTs that
>    do not carry all four clock-names (Jiaxing Hu)
>  - collect Jiaxing's Reviewed-by
> v1: https://lore.kernel.org/linux-rockchip/20260729092939.118779-1-royalnet026@xxxxxxxxx/
> 
> The same four id assignments are board-tested on RK3576 (ROCK 4D) as
> part of Jiaxing's RK3576 enablement series (v2 6/8), so the change has
> been exercised on two SoCs between us.
> 
> Verified on RK3588 (Orange Pi 5 Plus): after the change clk_summary
> shows one consumer handle per clock instead of four handles on aclk, the
> NPU still powers up and down cleanly through runtime PM, and a
> MobileNetV1 inference run via the Teflon TFLite delegate produces
> bit-identical output tensors to the unpatched driver.
> 
>  drivers/accel/rocket/rocket_core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/accel/rocket/rocket_core.c b/drivers/accel/rocket/rocket_core.c
> index b3b2fa9..5dd260b 100644
> --- a/drivers/accel/rocket/rocket_core.c
> +++ b/drivers/accel/rocket/rocket_core.c
> @@ -28,6 +28,10 @@ int rocket_core_init(struct rocket_core *core)
>  	if (err)
>  		return dev_err_probe(dev, err, "failed to get resets for core %d\n", core->index);
> 
> +	core->clks[0].id = "aclk";
> +	core->clks[1].id = "hclk";
> +	core->clks[2].id = "npu";
> +	core->clks[3].id = "pclk";
>  	err = devm_clk_bulk_get(dev, ARRAY_SIZE(core->clks), core->clks);
>  	if (err)
>  		return dev_err_probe(dev, err, "failed to get clocks for core %d\n", core->index);

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