linux-kernel - Re: [PATCH v10 2/3] clk: canaan: Add clock driver for Canaan K230

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Message-ID: <aXiuDAO7I6urJj09@duge-virtual-machine>
Date: Tue, 27 Jan 2026 20:22:36 +0800
From: Jiayu Du <jiayu.riscv@...c.iscas.ac.cn>
To: Xukai Wang <kingxukai@...omail.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Conor Dooley <conor@...nel.org>
Cc: linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
	Samuel Holland <samuel.holland@...ive.com>,
	Troy Mitchell <TroyMitchell988@...il.com>
Subject: Re: [PATCH v10 2/3] clk: canaan: Add clock driver for Canaan K230

On Tue, Jan 27, 2026 at 07:03:59PM +0800, Xukai Wang wrote:
> 
> On 2026/1/23 00:01, Jiayu Du wrote:
> > On Thu, Jan 22, 2026 at 07:40:29PM +0800, Xukai Wang wrote:
> >> On 2026/1/19 16:18, Jiayu Du wrote:
> >>>> +
> >>>> +K230_CLK_GATE_FORMAT(hs_hclk_src_gate,
> >>>> +		     K230_HS_HCLK_SRC_GATE,
> >>>> +		     0x18, 0, 0, 0,
> >>>> +		     &hs_hclk_high_src_rate.clk.hw);
> >>> Here, you replaced hs_hclk_high_gate(in v9) with hs_hclk_high_src_rate,
> >> I'm a bit confused, as I don't recall making these specific changes.
> >> Looking at the code below, the only difference between v9 and v10 is
> >> within the K230_CLK_GATE_FORMAT(hs_hclk_src_gate, ...) definition, where
> >> the second parameter changed from 1 to 0. Everything else appears
> >> consistent. Could you clarify which change you were referring to?
> >>> but after my board test, I find that when hs_hclk_high_gate is turned
> >>> off, the mmc/sd and other high-speed subsystems can not work. So maybe
> >>> you should not change the hs_hclk_high_gate to hs_hclk_high_src_rate.
> >> Regarding the clock management, I recommend explicitly enabling
> >> hs_hclk_high_gateas it will be closed by `close unused clocks`.
> > Sorry, you are right. It was me who made the changes locally. And I
> > saw your reply to this email[1], which you said According to the vendor's
> > code, the parent clock of hs_hclk_src is hs_hclk_high_src.
> >
> > Indeed, the parent clock of hs_hclk_src is hs_hclk_high_src. 
> 
> > but hs_hclk_high_gate is the gate of hs_hclk_high_src. 
> 
> No. It seems there is some confusion. The hs_hclk_high_src does not have
> a gate.

In this code segment of the vendor[1], it states that hs_hclk_high is
indeed the downstream gate of hs_hclk_high_src. Once hs_hclk_high is turned
off, all the high-speed peripherals such as USB, MMC, and SD will fail.
This indicates that in the hardware, the gate bit1 actually controls the
overall clock switch of the high speed system.

I understand that hs_sd0/1_ahb_gate should be enabled during the SD driver
probe, and hs_usb0/1_ahb_gate should be enabled during the USB driver probe,
but currently there is NO clear driver to ENABLE hi_hclk_high_gate. 

So in your code, I think hs_hclk_high_gate should be the gate of 
hs_hclk_high_src_rate. And hs_hclk_high_gate should be the parent of
hs_hclk_src_gate.

link: https://github.com/kendryte/k230_sdk/blob/main/src/little/linux/arch/riscv/boot/dts/kendryte/clock_provider.dtsi#L497 [1]

> 
> The clock tree is as follow:
> 
>        pll0_div4
>           hs_hclk_high_src_rate
>              hs_hclk_high_gate
>              hs_hclk_src_gate
>                 hs_hclk_src_rate
>                    hs_sd0_ahb_gate
>                    hs_sd1_ahb_gate
>                    hs_ssi1_ahb_gate
>                    hs_ssi2_ahb_gate
>                    hs_usb0_ahb_gate
>                    hs_usb1_ahb_gate
> 
> > So, what you mean is
> > that you will add the CLK_IS_CRITICAL flag to the hs_hclk_high_gate?
> No, I don't intend to add CLK_IS_CRITICAL flag. Instead, I recommend you
> to explicitly enable the clock by using clk_prepare_enable in your driver.

I think there is NO clear driver to ENABLE hi_hclk_high_gate.

Regards,
Jiayu Du

> >
> > Link: https://lore.kernel.org/all/159615d3-cc52-43be-bf6d-5fe717ef1cc4@zohomail.com/ [1]
> >
> > Regards,
> > Jiayu Du
> >