[PATCH] clk: meson: g12a: mark fclk_div2 as critical

[PATCH] clk: meson: g12a: mark fclk_div2 as critical

[Stefan Agner]

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,
 	},
 };
 
-- 
2.28.0

Re: [PATCH] clk: meson: g12a: mark fclk_div2 as critical

[Jerome Brunet]

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

Re: [PATCH] clk: meson: g12a: mark fclk_div2 as critical

[Anand Moon]

Hi Stefan,

On Fri, 28 Aug 2020 at 03:14, 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>
> ---

Thank you for this patch. I reported this a long time ago but could
not solve it.
Please add my
Tested-by: Anand Moon <linux.amoon@gmail.com>



>  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,
>         },
>  };
>
> --
> 2.28.0
>
>
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