linux-kernel - Re: [PATCH] clk: qcom: rpmh: Add note about sleep/wake state for BCMs

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Date:   Tue, 17 May 2022 14:16:55 -0500
From:   Alex Elder <elder@...aro.org>
To:     Stephen Boyd <swboyd@...omium.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        patches@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        Taniya Das <quic_tdas@...cinc.com>
Subject: Re: [PATCH] clk: qcom: rpmh: Add note about sleep/wake state for BCMs

On 5/17/22 2:09 PM, Stephen Boyd wrote:
> The sleep/wake state doesn't need to be set here because of specific
> RPMh behavior that carries over the active state when sleep/wake state
> hasn't been modified. Add a note to the code so we aren't tempted to set
> the sleep/wake states.
> 
> Cc: Alex Elder <elder@...aro.org>
> Cc: Taniya Das <quic_tdas@...cinc.com>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>

Looks good to me.  Thanks Stephen.

Reviewed-by: Alex Elder <elder@...aro.org>

> ---
> 
> This superseedes a previous patch[1] I sent that tried to fix this.
> 
>   drivers/clk/qcom/clk-rpmh.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/clk/qcom/clk-rpmh.c b/drivers/clk/qcom/clk-rpmh.c
> index aed907982344..c07cab6905cb 100644
> --- a/drivers/clk/qcom/clk-rpmh.c
> +++ b/drivers/clk/qcom/clk-rpmh.c
> @@ -274,6 +274,11 @@ static int clk_rpmh_bcm_send_cmd(struct clk_rpmh *c, bool enable)
>   		cmd.addr = c->res_addr;
>   		cmd.data = BCM_TCS_CMD(1, enable, 0, cmd_state);
>   
> +		/*
> +		 * Send only an active only state request. RPMh continues to
> +		 * use the active state when we're in sleep/wake state as long
> +		 * as the sleep/wake state has never been set.
> +		 */
>   		ret = clk_rpmh_send(c, RPMH_ACTIVE_ONLY_STATE, &cmd, enable);
>   		if (ret) {
>   			dev_err(c->dev, "set active state of %s failed: (%d)\n",
> 
> base-commit: 42226c989789d8da4af1de0c31070c96726d990c