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Subject: Re: [PATCH v7 08/20] clk: tegra: clk-super: Fix to enable PLLP
 branches to CPU
To:     Sowjanya Komatineni <skomatineni@nvidia.com>,
        thierry.reding@gmail.com, jonathanh@nvidia.com, tglx@linutronix.de,
        jason@lakedaemon.net, marc.zyngier@arm.com,
        linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com
Cc:     pdeschrijver@nvidia.com, pgaikwad@nvidia.com, sboyd@kernel.org,
        linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org,
        jckuo@nvidia.com, josephl@nvidia.com, talho@nvidia.com,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        mperttunen@nvidia.com, spatra@nvidia.com, robh+dt@kernel.org,
        devicetree@vger.kernel.org
References: <1564532424-10449-1-git-send-email-skomatineni@nvidia.com>
 <1564532424-10449-9-git-send-email-skomatineni@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <3ce20cbf-fe6f-c62b-c7b9-e3cad46f3381@gmail.com>
Date:   Wed, 31 Jul 2019 13:14:41 +0300
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31.07.2019 3:20, 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 and
> disables PLLP branches to CPU when not in use.
> 
> 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@nvidia.com>
> ---
>  drivers/clk/tegra/clk-super.c            | 14 ++++++++++++++
>  drivers/clk/tegra/clk-tegra-super-gen4.c |  2 +-
>  drivers/clk/tegra/clk.c                  | 14 ++++++++++++++
>  drivers/clk/tegra/clk.h                  |  5 +++++
>  4 files changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/tegra/clk-super.c b/drivers/clk/tegra/clk-super.c
> index 39ef31b46df5..e2a1e95a8db7 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);
> @@ -97,12 +100,23 @@ 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 & TEGRA210_CPU_CLK) &&
> +	    (index == CCLK_SRC_PLLP_OUT0 || index == CCLK_SRC_PLLP_OUT4))
> +		tegra_clk_set_pllp_out_cpu(true);
> +
>  	val &= ~((super_state_to_src_mask(mux)) << shift);
>  	val |= (index & (super_state_to_src_mask(mux))) << shift;
>  
>  	writel_relaxed(val, mux->reg);
>  	udelay(2);
>  
> +	/* disable PLLP branches to CPU if not used */
> +	if ((mux->flags & TEGRA210_CPU_CLK) &&
> +	    index != CCLK_SRC_PLLP_OUT0 && index != CCLK_SRC_PLLP_OUT4)
> +		tegra_clk_set_pllp_out_cpu(false);
> +
>  out:
>  	if (mux->lock)
>  		spin_unlock_irqrestore(mux->lock, flags);
> diff --git a/drivers/clk/tegra/clk-tegra-super-gen4.c b/drivers/clk/tegra/clk-tegra-super-gen4.c
> index cdfe7c9697e1..888d76b01c75 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);
> +					TEGRA210_CPU_CLK, 4, 8, 0, NULL);

Don't we want a clarifying comment for cclk_lp telling why it doesn't
have the TEGRA210_CPU_CLK flag?

>  		} else {
>  			clk = tegra_clk_register_super_mux("cclk_g",
>  					gen_info->cclk_g_parents,
> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
> index 573e3c967ae1..eb08047fd02f 100644
> --- a/drivers/clk/tegra/clk.c
> +++ b/drivers/clk/tegra/clk.c
> @@ -23,6 +23,7 @@
>  #define CLK_OUT_ENB_W			0x364
>  #define CLK_OUT_ENB_X			0x280
>  #define CLK_OUT_ENB_Y			0x298
> +#define CLK_ENB_PLLP_OUT_CPU		BIT(31)
>  #define CLK_OUT_ENB_SET_L		0x320
>  #define CLK_OUT_ENB_CLR_L		0x324
>  #define CLK_OUT_ENB_SET_H		0x328
> @@ -199,6 +200,19 @@ const struct tegra_clk_periph_regs *get_reg_bank(int clkid)
>  	}
>  }
>  
> +void tegra_clk_set_pllp_out_cpu(bool enable)
> +{
> +	u32 val;
> +
> +	val = readl_relaxed(clk_base + CLK_OUT_ENB_Y);
> +	if (enable)
> +		val |= CLK_ENB_PLLP_OUT_CPU;
> +	else
> +		val &= ~CLK_ENB_PLLP_OUT_CPU;
> +
> +	writel_relaxed(val, clk_base + CLK_OUT_ENB_Y);
> +}
> +
>  struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
>  {
>  	clk_base = regs;
> diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
> index d61e61eebf4a..f8de447f505b 100644
> --- a/drivers/clk/tegra/clk.h
> +++ b/drivers/clk/tegra/clk.h
> @@ -687,6 +687,9 @@ 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.
> + * TEGRA210_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
> + * additional bit PLLP_OUT_CPU for gen5 super clock.
>   */
>  struct tegra_clk_super_mux {
>  	struct clk_hw	hw;
> @@ -703,6 +706,7 @@ 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 TEGRA210_CPU_CLK BIT(1)
>  
>  extern const struct clk_ops tegra_clk_super_ops;
>  struct clk *tegra_clk_register_super_mux(const char *name,
> @@ -849,6 +853,7 @@ int tegra_pll_p_div_to_hw(struct tegra_clk_pll *pll, u8 p_div);
>  int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
>  		 u8 frac_width, u8 flags);
>  void tegra_clk_osc_resume(void __iomem *clk_base);
> +void tegra_clk_set_pllp_out_cpu(bool enable);
>  
>  
>  /* Combined read fence with delay */
>