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In-Reply-To: <20220413071318.244912-1-codrin.ciubotariu@microchip.com>
References: <20220413071318.244912-1-codrin.ciubotariu@microchip.com>
Subject: Re: [PATCH] clk: at91: generated: consider range when calculating best rate
From:   Stephen Boyd <sboyd@kernel.org>
Cc:     mturquette@baylibre.com, nicolas.ferre@microchip.com,
        alexandre.belloni@bootlin.com, claudiu.beznea@microchip.com,
        Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
To:     Codrin Ciubotariu <codrin.ciubotariu@microchip.com>,
        linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Thu, 21 Apr 2022 18:12:14 -0700
User-Agent: alot/0.10
Message-Id: <20220422011216.A4A23C385A5@smtp.kernel.org>
Precedence: bulk

Quoting Codrin Ciubotariu (2022-04-13 00:13:18)
> clk_generated_best_diff() helps in finding the parent and the divisor to
> compute a rate closest to the required one. However, it doesn't take into
> account the request's range for the new rate. Make sure the new rate
> is within the required range.
>=20
> Fixes: 8a8f4bf0c480 ("clk: at91: clk-generated: create function to find b=
est_diff")
> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
> ---

Is this fixing anything real or it's just a thing that you noticed and
sent a patch to fix?

>  drivers/clk/at91/clk-generated.c | 4 ++++
>  1 file changed, 4 insertions(+)
>=20
> diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-gene=
rated.c
> index 23cc8297ec4c..d429ba52a719 100644
> --- a/drivers/clk/at91/clk-generated.c
> +++ b/drivers/clk/at91/clk-generated.c
> @@ -117,6 +117,10 @@ static void clk_generated_best_diff(struct clk_rate_=
request *req,
>                 tmp_rate =3D parent_rate;
>         else
>                 tmp_rate =3D parent_rate / div;
> +
> +       if (tmp_rate < req->min_rate || tmp_rate > req->max_rate)
> +               return;
> +
>         tmp_diff =3D abs(req->rate - tmp_rate);
> =20
>         if (*best_diff < 0 || *best_diff >=3D tmp_diff) {