linux-kernel - Re: [PATCH v6 06/18] clk: qcom: clk-krait: unlock spin after mux completion

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Date:   Thu, 24 Mar 2022 18:04:41 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Andy Gross <agross@...nel.org>,
        Ansuel Smith <ansuelsmth@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 06/18] clk: qcom: clk-krait: unlock spin after mux completion

Quoting Ansuel Smith (2022-03-21 16:15:36)
> Unlock spinlock after the mux switch is completed to prevent any corner
> case of mux request while the switch still needs to be done.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---

Please add a Fixes tag.

>  drivers/clk/qcom/clk-krait.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
> index 59f1af415b58..e447fcc3806d 100644
> --- a/drivers/clk/qcom/clk-krait.c
> +++ b/drivers/clk/qcom/clk-krait.c
> @@ -32,11 +32,12 @@ static void __krait_mux_set_sel(struct krait_mux_clk *mux, int sel)
>                 regval |= (sel & mux->mask) << (mux->shift + LPL_SHIFT);
>         }
>         krait_set_l2_indirect_reg(mux->offset, regval);
> -       spin_unlock_irqrestore(&krait_clock_reg_lock, flags);
>  
>         /* Wait for switch to complete. */
>         mb();
>         udelay(1);
> +

Please add a comment here indicating we want to make sure the mux
register isn't modified while switching to the new parent.

> +       spin_unlock_irqrestore(&krait_clock_reg_lock, flags);
>  }
>