linux-kernel - Re: [PATCH] clk: qcom: gdsc: Ensure regulator init state matches GDSC state

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Message-ID: <YNuLHWkUwyml26Uk@yoga>
Date:   Tue, 29 Jun 2021 16:05:33 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        dmitry.baryshkov@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: gdsc: Ensure regulator init state matches
 GDSC state

On Fri 25 Jun 17:54 CDT 2021, Bjorn Andersson wrote:

> As GDSCs are registered and found to be already enabled
> gdsc_toggle_logic() will be invoked for votable GDSCs and ensure that
> the vote is matching the hardware state. Part of this the related
> regulator will be enabled.
> 
> But for non-votable GDSCs the regulator and GDSC status will be out of
> sync and as the GDSC is later disabled regulator_disable() will face an
> unbalanced enable-count, or something might turn off the supply under
> the feet of the GDSC.
> 
> So ensure that the regulator is enabled even for non-votable GDSCs.
> 
> Cc: stable@...r.kernel.org
> Fixes: 37416e554961 ("clk: qcom: gdsc: Handle GDSC regulator supplies")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  drivers/clk/qcom/gdsc.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 51ed640e527b..f7e7759cdb90 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -359,10 +359,17 @@ static int gdsc_init(struct gdsc *sc)
>  
>  	/*
>  	 * Votable GDSCs can be ON due to Vote from other masters.
> -	 * If a Votable GDSC is ON, make sure we have a Vote.
> +	 * If a Votable GDSC is ON, make sure we have a Vote. If
> +	 * non-votable, ensure that the supply is kept enabled (as
> +	 * is done by gdsc_enable).
>  	 */
> -	if ((sc->flags & VOTABLE) && on)
> +	if ((sc->flags & VOTABLE) && on) {
>  		gdsc_enable(&sc->pd);
> +	} else if (on) {

I somehow lost the check for sc->rsupply != NULL while trying to make
this readable. In other words, this is broken.

Regards,
Bjorn

> +		ret = regulator_enable(sc->rsupply);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
>  	/*
>  	 * Make sure the retain bit is set if the GDSC is already on, otherwise
> -- 
> 2.29.2
>