linux-kernel - Re: [PATCH 1/4] clk: qcom: clk-hfpll: use poll

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Date:   Fri, 29 Apr 2022 17:42:22 +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 1/4] clk: qcom: clk-hfpll: use poll_timeout macro

On 29/04/2022 15:01, Ansuel Smith wrote:
> Use regmap_read_poll_timeout macro instead of do-while structure to tidy
> things up. Also set a timeout to prevent any sort of system stall.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>

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

> ---
>   drivers/clk/qcom/clk-hfpll.c | 15 +++++++++------
>   1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/clk/qcom/clk-hfpll.c b/drivers/clk/qcom/clk-hfpll.c
> index e847d586a73a..7dd17c184b69 100644
> --- a/drivers/clk/qcom/clk-hfpll.c
> +++ b/drivers/clk/qcom/clk-hfpll.c
> @@ -72,13 +72,16 @@ static void __clk_hfpll_enable(struct clk_hw *hw)
>   	regmap_update_bits(regmap, hd->mode_reg, PLL_RESET_N, PLL_RESET_N);
>   
>   	/* Wait for PLL to lock. */
> -	if (hd->status_reg) {
> -		do {
> -			regmap_read(regmap, hd->status_reg, &val);
> -		} while (!(val & BIT(hd->lock_bit)));
> -	} else {
> +	if (hd->status_reg)
> +		/*
> +		 * Busy wait. Should never timeout, we add a timeout to
> +		 * prevent any sort of stall.
> +		 */
> +		regmap_read_poll_timeout(regmap, hd->status_reg, val,
> +					 !(val & BIT(hd->lock_bit)), 0,
> +					 100 * USEC_PER_MSEC);
> +	else
>   		udelay(60);
> -	}
>   
>   	/* Enable PLL output. */
>   	regmap_update_bits(regmap, hd->mode_reg, PLL_OUTCTRL, PLL_OUTCTRL);


-- 
With best wishes
Dmitry