linux-kernel - Re: [PATCH V6 09/21] clk: tegra: clk-super: Fix to enable PLLP branches to CPU

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Date:   Mon, 22 Jul 2019 00:16:37 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, tglx@...utronix.de,
        jason@...edaemon.net, marc.zyngier@....com,
        linus.walleij@...aro.org, stefan@...er.ch, mark.rutland@....com
Cc:     pdeschrijver@...dia.com, pgaikwad@...dia.com, sboyd@...nel.org,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
        jckuo@...dia.com, josephl@...dia.com, talho@...dia.com,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        mperttunen@...dia.com, spatra@...dia.com, robh+dt@...nel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH V6 09/21] clk: tegra: clk-super: Fix to enable PLLP
 branches to CPU

21.07.2019 22:40, Sowjanya Komatineni пишет:
> This patch has a fix to enable PLLP branches to CPU before changing
> the CPU clusters clock source to PLLP for Gen5 Super clock.
> 
> During system suspend entry and exit, CPU source will be switched
> to PLLP and this needs PLLP branches to be enabled to CPU prior to
> the switch.
> 
> On system resume, warmboot code enables PLLP branches to CPU and
> powers up the CPU with PLLP clock source.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
>  drivers/clk/tegra/clk-super.c            | 11 +++++++++++
>  drivers/clk/tegra/clk-tegra-super-gen4.c |  4 ++--
>  drivers/clk/tegra/clk.h                  |  4 ++++
>  3 files changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-super.c b/drivers/clk/tegra/clk-super.c
> index 39ef31b46df5..d73c587e4853 100644
> --- a/drivers/clk/tegra/clk-super.c
> +++ b/drivers/clk/tegra/clk-super.c
> @@ -28,6 +28,9 @@
>  #define super_state_to_src_shift(m, s) ((m->width * s))
>  #define super_state_to_src_mask(m) (((1 << m->width) - 1))
>  
> +#define CCLK_SRC_PLLP_OUT0 4
> +#define CCLK_SRC_PLLP_OUT4 5
> +
>  static u8 clk_super_get_parent(struct clk_hw *hw)
>  {
>  	struct tegra_clk_super_mux *mux = to_clk_super_mux(hw);
> @@ -97,6 +100,14 @@ static int clk_super_set_parent(struct clk_hw *hw, u8 index)
>  		if (index == mux->div2_index)
>  			index = mux->pllx_index;
>  	}
> +
> +	/*
> +	 * Enable PLLP branches to CPU before selecting PLLP source
> +	 */
> +	if ((mux->flags & TEGRA_CPU_CLK) &&
> +	    ((index == CCLK_SRC_PLLP_OUT0) || (index == CCLK_SRC_PLLP_OUT4)))
> +		tegra_clk_set_pllp_out_cpu(true);

Should somewhere here be tegra_clk_set_pllp_out_cpu(false) when
switching from PLLP?

>  	val &= ~((super_state_to_src_mask(mux)) << shift);
>  	val |= (index & (super_state_to_src_mask(mux))) << shift;
>  
> diff --git a/drivers/clk/tegra/clk-tegra-super-gen4.c b/drivers/clk/tegra/clk-tegra-super-gen4.c
> index cdfe7c9697e1..cd208d0eca2a 100644
> --- a/drivers/clk/tegra/clk-tegra-super-gen4.c
> +++ b/drivers/clk/tegra/clk-tegra-super-gen4.c
> @@ -180,7 +180,7 @@ static void __init tegra_super_clk_init(void __iomem *clk_base,
>  					gen_info->num_cclk_g_parents,
>  					CLK_SET_RATE_PARENT,
>  					clk_base + CCLKG_BURST_POLICY,
> -					0, 4, 8, 0, NULL);
> +					TEGRA_CPU_CLK, 4, 8, 0, NULL);
>  		} else {
>  			clk = tegra_clk_register_super_mux("cclk_g",
>  					gen_info->cclk_g_parents,
> @@ -201,7 +201,7 @@ static void __init tegra_super_clk_init(void __iomem *clk_base,
>  					gen_info->num_cclk_lp_parents,
>  					CLK_SET_RATE_PARENT,
>  					clk_base + CCLKLP_BURST_POLICY,
> -					0, 4, 8, 0, NULL);
> +					TEGRA_CPU_CLK, 4, 8, 0, NULL);
>  		} else {
>  			clk = tegra_clk_register_super_mux("cclk_lp",
>  					gen_info->cclk_lp_parents,
> diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
> index ac6de3a0b91f..c357b49e49b0 100644
> --- a/drivers/clk/tegra/clk.h
> +++ b/drivers/clk/tegra/clk.h
> @@ -694,6 +694,9 @@ struct clk *tegra_clk_register_periph_data(void __iomem *clk_base,
>   * Flags:
>   * TEGRA_DIVIDER_2 - LP cluster has additional divider. This flag indicates
>   *     that this is LP cluster clock.
> + * TEGRA_CPU_CLK - This flag indicates this is CPU cluster clock. To use PLLP
> + * for CPU clock source, need to enable PLLP branches to CPU by setting the
> + * additional bit PLLP_OUT_CPU for gen5 super clock.
>   */
>  struct tegra_clk_super_mux {
>  	struct clk_hw	hw;
> @@ -710,6 +713,7 @@ struct tegra_clk_super_mux {
>  #define to_clk_super_mux(_hw) container_of(_hw, struct tegra_clk_super_mux, hw)
>  
>  #define TEGRA_DIVIDER_2 BIT(0)
> +#define TEGRA_CPU_CLK	BIT(1)

I'd name this TEGRA210_CPU_CLK for clarity.

>  extern const struct clk_ops tegra_clk_super_ops;
>  struct clk *tegra_clk_register_super_mux(const char *name,
> 

Will be better to move the tegra_clk_set_pllp_out_cpu() definition into
this patch, otherwise this looks inconsistent for reviewer.