linux-kernel - Re: [PATCH V4 2/2] clk: scmi: support state_ctrl

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Date: Tue, 23 Jan 2024 11:13:16 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>, sboyd@...nel.org
Cc: cristian.marussi@....com, mturquette@...libre.com,
	Sudeep Holla <sudeep.holla@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V4 2/2] clk: scmi: support state_ctrl_forbidden

On Sun, Jan 21, 2024 at 07:09:01PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....com>
> 
> Some clocks may exported to linux, while those clocks are not allowed
> to configure by Linux. For example:
> 
> SYS_CLK1-----
>              \
> 	     --MUX--->MMC1_CLK
>              /
> SYS_CLK2-----
> 
> MMC1 needs set parent, so SYS_CLK1 and SYS_CLK2 are exported to Linux,
> then the clk propagation will touch SYS_CLK1 or SYS_CLK2.
> So we need bypass the failure for SYS_CLK1 or SYS_CLK2 when enable
> the clock of MMC1, adding scmi_no_state_ctrl_clk_ops to use software
> enable counter, while not calling scmi api.
>

I would rewrite the commit message something like:
"
    clk: scmi: Add support for forbidden clock state controls

    Some clocks may be exported to OS agent, while certain configurations/
    access to those clocks are restricted to the OS agent by the SCMI platform
    firmware. For example:

    SYS_CLK1-----
                 \
                 --MUX--->MMC1_CLK
                 /
    SYS_CLK2-----

    MMC1_CLK needs to set parent as part of it initialisation and enabling.
    SYS_CLK1 and SYS_CLK2 are exported to the OS agent. The clk propagation
    will access SYS_CLK1 or SYS_CLK2 based on the configuration. However,
    we need bypass the failure to access SYS_CLK1 or SYS_CLK2 when MMC1_CLK
    is accessed and enabled.

    Add a separate scmi_no_state_ctrl clk_ops where the calls to the SCMI
    platform firmware are avoided if the access is not permitted.
"
No need to repost.

I need Stephen's ack to take this together with scmi clk changes.

--
Regards,
Sudeep