linux-kernel - Re: [PATCH] clk: scmi: add is

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZqOIFfkxylcdIIFB@pluto>
Date: Fri, 26 Jul 2024 12:27:17 +0100
From: Cristian Marussi <cristian.marussi@....com>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc: sudeep.holla@....com, cristian.marussi@....com, mturquette@...libre.com,
	sboyd@...nel.org, linux-clk@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	arm-scmi@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH] clk: scmi: add is_prepared hook

On Thu, Jul 25, 2024 at 05:07:41PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....com>
> 

.... one more remark..

> Some clks maybe default enabled by hardware, so add is_prepared hook
> to get the status of the clk. Then when disabling unused clks, those
> unused clks but default hardware on clks could be in off state to save
> power.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/clk/clk-scmi.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
> index d86a02563f6c..d2d370337ba5 100644
> --- a/drivers/clk/clk-scmi.c
> +++ b/drivers/clk/clk-scmi.c
> @@ -142,6 +142,20 @@ static void scmi_clk_disable(struct clk_hw *hw)
>  	scmi_proto_clk_ops->disable(clk->ph, clk->id, NOT_ATOMIC);
>  }
>  
> +static int scmi_clk_is_enabled(struct clk_hw *hw)
> +{
> +	int ret;
> +	bool enabled = false;
> +	struct scmi_clk *clk = to_scmi_clk(hw);
> +
> +	ret = scmi_proto_clk_ops->state_get(clk->ph, clk->id, &enabled, NOT_ATOMIC);
> +	if (ret)
> +		dev_warn(clk->dev,
> +			 "Failed to get state for clock ID %d\n", clk->id);
> +
> +	return !!enabled;
> +}
> +
>  static int scmi_clk_atomic_enable(struct clk_hw *hw)
>  {
>  	struct scmi_clk *clk = to_scmi_clk(hw);
> @@ -280,6 +294,7 @@ scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
>  		} else {
>  			ops->prepare = scmi_clk_enable;
>  			ops->unprepare = scmi_clk_disable;
> +			ops->is_prepared = scmi_clk_is_enabled;

... you should NOT add the is_prepared ops here, since this would mean
that you will have the is_prepared ops available only when
SCMI_CLK_STATE_CTRL_SUPPORTED, WHILE you most probably want to be able
to check (non atomically) the current enabled-status for a clock EVEN IF
you are allowed to change its state...please add the is_prepared in the
else-branch down below where the ATOMIC is_enabled is added

Thanks,
Cristian