linux-kernel - Re: [PATCH v2] clk: meson: Fix the determine rate error in clk_regmap_divider_ro

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Message-ID: <8a006cf8-2f65-43bf-a990-712fba01f0fb@amlogic.com>
Date: Tue, 12 Nov 2024 21:04:07 +0800
From: Chuan Liu <chuan.liu@...ogic.com>
To: Neil Armstrong <neil.armstrong@...aro.org>,
 Jerome Brunet <jbrunet@...libre.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Kevin Hilman <khilman@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 Jian Hu <jian.hu@...ogic.com>, Dmitry Rokosov <ddrokosov@...rdevices.ru>,
 Yu Tu <yu.tu@...ogic.com>
Cc: linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clk: meson: Fix the determine rate error in
 clk_regmap_divider_ro_ops


On 11/12/2024 8:57 PM, Chuan Liu via B4 Relay wrote:
> [Some people who received this message don't often get email from devnull+chuan.liu.amlogic.com@...nel.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> [ EXTERNAL EMAIL ]
>
> From: Chuan Liu <chuan.liu@...ogic.com>
>
> The rate determined by calling clk_regmap_divider_ro_ops with
> clk_regmap_div_determine_rate is not RO, which will result in the
> unexpected modification of the frequency of its children when setting
> the rate of a clock that references clk_regmap_divider_ro_ops.
>
> Fiexs: ea11dda9e091 ("clk: meson: add regmap clocks")

typo of "Fiexs", corrected in the next version.

> Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>
> ---
> Background: During the execution of clk_set_rate(), the function
> clk_core_round_rate_nolock() is called to calculate the matching rate
> and save it to 'core->new_rate'. At the same time, it recalculates and
> updates its 'child->newrate'. Finally, clk_change_rate() is called to
> set all 'new_rates'.
> ---
> Changes in v2:
> - Remove the CLK_DIVIDER_READ_ONLY judgment logic in
> clk_regmap_div_determine_rate().
> - Add clk_regmap_div_ro_determine_rate().
> - Link to v1: https://lore.kernel.org/r/20241111-fix_childclk_of_roclk_has_been_tampered_with-v1-1-f8c1b6ffdcb0@amlogic.com
> ---
>   drivers/clk/meson/clk-regmap.c | 36 ++++++++++++++++++++----------------
>   1 file changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/clk/meson/clk-regmap.c b/drivers/clk/meson/clk-regmap.c
> index 07f7e441b916..edf65ca92c7a 100644
> --- a/drivers/clk/meson/clk-regmap.c
> +++ b/drivers/clk/meson/clk-regmap.c
> @@ -80,21 +80,6 @@ static int clk_regmap_div_determine_rate(struct clk_hw *hw,
>   {
>          struct clk_regmap *clk = to_clk_regmap(hw);
>          struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk);
> -       unsigned int val;
> -       int ret;
> -
> -       /* if read only, just return current value */
> -       if (div->flags & CLK_DIVIDER_READ_ONLY) {
> -               ret = regmap_read(clk->map, div->offset, &val);
> -               if (ret)
> -                       return ret;
> -
> -               val >>= div->shift;
> -               val &= clk_div_mask(div->width);
> -
> -               return divider_ro_determine_rate(hw, req, div->table,
> -                                                div->width, div->flags, val);
> -       }
>
>          return divider_determine_rate(hw, req, div->table, div->width,
>                                        div->flags);
> @@ -127,9 +112,28 @@ const struct clk_ops clk_regmap_divider_ops = {
>   };
>   EXPORT_SYMBOL_NS_GPL(clk_regmap_divider_ops, CLK_MESON);
>
> +static int clk_regmap_div_ro_determine_rate(struct clk_hw *hw,
> +                                           struct clk_rate_request *req)
> +{
> +       struct clk_regmap *clk = to_clk_regmap(hw);
> +       struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk);
> +       unsigned int val;
> +       int ret;
> +
> +       ret = regmap_read(clk->map, div->offset, &val);
> +       if (ret)
> +               return ret;
> +
> +       val >>= div->shift;
> +       val &= clk_div_mask(div->width);
> +
> +       return divider_ro_determine_rate(hw, req, div->table, div->width,
> +                                        div->flags, val);
> +}
> +
>   const struct clk_ops clk_regmap_divider_ro_ops = {
>          .recalc_rate = clk_regmap_div_recalc_rate,
> -       .determine_rate = clk_regmap_div_determine_rate,
> +       .determine_rate = clk_regmap_div_ro_determine_rate,
>   };
>   EXPORT_SYMBOL_NS_GPL(clk_regmap_divider_ro_ops, CLK_MESON);
>
>
> ---
> base-commit: 664988eb47dd2d6ae1d9e4188ec91832562f8f26
> change-id: 20241111-fix_childclk_of_roclk_has_been_tampered_with-61dbcc623746
>
> Best regards,
> --
> Chuan Liu <chuan.liu@...ogic.com>
>
>