Re: [PATCH v6 09/10] clk: stm32: Fix ltdc's clock turn off by clk_disable_unused() after system enter shell

[Dillon Min <dillon.minfei@gmail.com>]

Hi Gabriel

I guess you are the maintainer of stm32 clk subsystem from [1], Could
you help to review this patch, just give a brief of the history:

- this patch was acked by Stephen Boyd at [2].
- reviewed by Patrice Chotard at [3].

Without this patch , the kernel will turn off ltdc's clk after the
system reach shell.

[1] https://lore.kernel.org/lkml/AM8PR10MB4785545DC980090C1E7D66B281009@AM8PR10MB4785.EURPRD10.PROD.OUTLOOK.COM/

[2] https://lore.kernel.org/linux-arm-kernel/159056850835.88029.9264848839121822798@swboyd.mtv.corp.google.com/

[3] https://lore.kernel.org/lkml/6915fa2a-e211-476f-8317-6825e280c322@foss.st.com/#t

Best Regards
Dillon

On Tue, 19 Oct 2021 at 16:44, Dillon Min <dillon.minfei@gmail.com> wrote:
>
> stm32's clk driver register two ltdc gate clk to clk core by
> clk_hw_register_gate() and clk_hw_register_composite()
>
> first: 'stm32f429_gates[]', clk name is 'ltdc', which no user to use.
> second: 'stm32f429_aux_clk[]', clk name is 'lcd-tft', used by ltdc driver
>
> both of them point to the same offset of stm32's RCC register. after
> kernel enter console, clk core turn off ltdc's clk as 'stm32f429_gates[]'
> is no one to use. but, actually 'stm32f429_aux_clk[]' is in use.
>
> stm32f469/746/769 have the same issue, fix it.
>
> Fixes: daf2d117cbca ("clk: stm32f4: Add lcd-tft clock")
> Acked-by: Stephen Boyd <sboyd@kernel.org>
> Link: https://lore.kernel.org/linux-arm-kernel/1590564453-24499-7-git-send-email-dillon.minfei@gmail.com/
> Link: https://lore.kernel.org/lkml/CAPTRvHkf0cK_4ZidM17rPo99gWDmxgqFt4CDUjqFFwkOeQeFDg@mail.gmail.com/
> Signed-off-by: Dillon Min <dillon.minfei@gmail.com>
> ---
> v6: no change.
>
>  drivers/clk/clk-stm32f4.c | 4 ----
>  1 file changed, 4 deletions(-)
>
> diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c
> index af46176ad053..473dfe632cc5 100644
> --- a/drivers/clk/clk-stm32f4.c
> +++ b/drivers/clk/clk-stm32f4.c
> @@ -129,7 +129,6 @@ static const struct stm32f4_gate_data stm32f429_gates[] __initconst = {
>         { STM32F4_RCC_APB2ENR, 20,      "spi5",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 21,      "spi6",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 22,      "sai1",         "apb2_div" },
> -       { STM32F4_RCC_APB2ENR, 26,      "ltdc",         "apb2_div" },
>  };
>
>  static const struct stm32f4_gate_data stm32f469_gates[] __initconst = {
> @@ -211,7 +210,6 @@ static const struct stm32f4_gate_data stm32f469_gates[] __initconst = {
>         { STM32F4_RCC_APB2ENR, 20,      "spi5",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 21,      "spi6",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 22,      "sai1",         "apb2_div" },
> -       { STM32F4_RCC_APB2ENR, 26,      "ltdc",         "apb2_div" },
>  };
>
>  static const struct stm32f4_gate_data stm32f746_gates[] __initconst = {
> @@ -286,7 +284,6 @@ static const struct stm32f4_gate_data stm32f746_gates[] __initconst = {
>         { STM32F4_RCC_APB2ENR, 21,      "spi6",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 22,      "sai1",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 23,      "sai2",         "apb2_div" },
> -       { STM32F4_RCC_APB2ENR, 26,      "ltdc",         "apb2_div" },
>  };
>
>  static const struct stm32f4_gate_data stm32f769_gates[] __initconst = {
> @@ -364,7 +361,6 @@ static const struct stm32f4_gate_data stm32f769_gates[] __initconst = {
>         { STM32F4_RCC_APB2ENR, 21,      "spi6",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 22,      "sai1",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 23,      "sai2",         "apb2_div" },
> -       { STM32F4_RCC_APB2ENR, 26,      "ltdc",         "apb2_div" },
>         { STM32F4_RCC_APB2ENR, 30,      "mdio",         "apb2_div" },
>  };
>
> --
> 2.7.4
>