Re: [PATCH v15 01/15] accel/rocket: request the core clocks by name

["Heiko Stübner" <heiko@sntech.de>]

Am Dienstag, 3. November 2026, 23:42:19 Mitteleuropäische Normalzeit schrieb Heiko Stübner:
> Am Sonntag, 1. November 2026, 09:22:53 Mitteleuropäische Normalzeit schrieb Jiaxing Hu:
> > From: Igor Paunovic <royalnet026@gmail.com>
> > 
> > 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@gmail.com>
> > Tested-by: Sidong Yang <sidong.yang@furiosa.ai>
> > Tested-by: Diederik de Haas <diederik@cknow-tech.com>  # NanoPC-T6 LTS, NanoPC-T6 Plus
> > Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
> > Reviewed-by: Jiaxing Hu <gahing@gahingwoo.com>
> > Signed-off-by: Jiaxing Hu <gahing@gahingwoo.com>
> 
> Reviewed-by: Heiko Stuebner <heiko@sntech.de>
> 
> nit: the commit description could be way shorter, for that small change.

note-to-self: also part of the DVFS series