linux-kernel - Re: [PATCH 2/4] clk: qcom: clk-krait: unlock spin after mux completion

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Date:   Fri, 29 Apr 2022 17:41:40 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Ansuel Smith <ansuelsmth@...il.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sricharan R <sricharan@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] clk: qcom: clk-krait: unlock spin after mux
 completion

On 29/04/2022 15:01, Ansuel Smith wrote:
> Unlock spinlock after the mux switch is completed to prevent any corner
> case of mux request while the switch still needs to be done.
> 
> Fixes: 4d7dc77babfe ("clk: qcom: Add support for Krait clocks")
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

> ---
>   drivers/clk/qcom/clk-krait.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
> index 59f1af415b58..90046428693c 100644
> --- a/drivers/clk/qcom/clk-krait.c
> +++ b/drivers/clk/qcom/clk-krait.c
> @@ -32,11 +32,16 @@ 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);
> +
> +	/*
> +	 * Unlock now to make sure the mux register is not
> +	 * modified while switching to the new parent.
> +	 */
> +	spin_unlock_irqrestore(&krait_clock_reg_lock, flags);
>   }
>   
>   static int krait_mux_set_parent(struct clk_hw *hw, u8 index)


-- 
With best wishes
Dmitry