linux-kernel - Re: [PATCH 4.19 29/74] clk: qcom: regmap-mux: fix parent clock lookup

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Message-ID: <20211215091623.GA15796@amd>
Date:   Wed, 15 Dec 2021 10:16:24 +0100
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCH 4.19 29/74] clk: qcom: regmap-mux: fix parent clock lookup

Hi!

> The function mux_get_parent() uses qcom_find_src_index() to find the
> parent clock index, which is incorrect: qcom_find_src_index() uses src
> enum for the lookup, while mux_get_parent() should use cfg field (which
> corresponds to the register value). Add qcom_find_cfg_index() function
> doing this kind of lookup and use it for mux parent lookup.

This appears to have problems with error handling.

> +++ b/drivers/clk/qcom/clk-regmap-mux.c
> @@ -36,7 +36,7 @@ static u8 mux_get_parent(struct clk_hw *
>  	val &= mask;
>  
>  	if (mux->parent_map)
> -		return qcom_find_src_index(hw, mux->parent_map, val);
> +		return qcom_find_cfg_index(hw, mux->parent_map, val);
>  
>  	return val;
>  }

So this returns u8.

> +int qcom_find_cfg_index(struct clk_hw *hw, const struct parent_map *map, u8 cfg)
> +{
> +	int i, num_parents = clk_hw_get_num_parents(hw);
> +
> +	for (i = 0; i < num_parents; i++)
> +		if (cfg == map[i].cfg)
> +			return i;
> +
> +	return -ENOENT;
> +}

In case of error, -ENOENT will be cast to u8 in caller. I don't
believe that is correct.

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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