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From:   Jerome Brunet <jbrunet@baylibre.com>
To:     Stefan Agner <stefan@agner.ch>, narmstrong@baylibre.com
Cc:     mturquette@baylibre.com, sboyd@kernel.org, khilman@baylibre.com,
        linux-amlogic@lists.infradead.org, linux-clk@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH] clk: meson: g12a: mark fclk_div2 as critical
In-reply-to: <c33df0ebe8be16b56741ce7f873221ab9087a0a6.1598564619.git.stefan@agner.ch>
Date:   Fri, 28 Aug 2020 15:52:24 +0200
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On Thu 27 Aug 2020 at 23:43, Stefan Agner <stefan@agner.ch> wrote:

> On Amlogic Meson G12b platform, similar to fclk_div3, the fclk_div2
> seems to be necessary for the system to operate correctly as well.
>
> Typically, the clock also gets chosen by the eMMC peripheral. This
> probably masked the problem so far. However, when booting from a SD
> card the clock seems to get disabled which leads to a system freeze.
>
> Let's mark this clock as critical, fixing boot from SD card on G12b
> platforms.
>
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
>  drivers/clk/meson/g12a.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c
> index fad616cac01e..2214b974f748 100644
> --- a/drivers/clk/meson/g12a.c
> +++ b/drivers/clk/meson/g12a.c
> @@ -298,6 +298,7 @@ static struct clk_regmap g12a_fclk_div2 = {
>  			&g12a_fclk_div2_div.hw
>  		},
>  		.num_parents = 1,
> +		.flags = CLK_IS_CRITICAL,
>  	},
>  };

Hi Stephan,

Thanks for reporting and fixing this. That's unfortunately the things we
have to find the "hard way"

Could you please:
1) add a Fixes tag to commit description so stable can pick it up

Fixes: 085a4ea93d54 ("clk: meson: g12a: add peripheral clock controller")

2) Add a comment similar to the comment block of fdiv3 so we are pretty
clear why this clock needs to be critical and don't have to dig in
history find out.

Also please Cc Marek Szyprowski <m.szyprowski@samsung.com> ... you guys
apparently found this at them time :)

Thanks