linux-kernel - Re: [PATCH 2/5] clk: imx: imx8ulp: Add divider closest support to get more accurate clock rate

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Date:   Sun, 9 Apr 2023 17:09:42 +0300
From:   Abel Vesa <abel.vesa@...aro.org>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     abelvesa@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jacky Bai <ping.bai@....com>, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 2/5] clk: imx: imx8ulp: Add divider closest support to
 get more accurate clock rate

On 23-03-31 14:38:11, Peng Fan (OSS) wrote:
> From: Jacky Bai <ping.bai@....com>
> 
> If a divider's parent clock has fractional part, it will hard to round out a
> more accurate clock rate for this divider, add the 'CLK_DIVIDER_ROUND_CLOSEST' flags
> for such divider to get a more accurate clock rate.
> 
> Reviewed-by: Peng Fan <peng.fan@....com>
> Signed-off-by: Jacky Bai <ping.bai@....com>
> Signed-off-by: Peng Fan <peng.fan@....com>

Reviewed-by: Abel Vesa <abel.vesa@...aro.org>

> ---
>  drivers/clk/imx/clk-imx8ulp.c | 16 ++++++++--------
>  drivers/clk/imx/clk.h         |  9 +++++++++
>  2 files changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/clk/imx/clk-imx8ulp.c b/drivers/clk/imx/clk-imx8ulp.c
> index 89121037a8f0..3cf4b094dfff 100644
> --- a/drivers/clk/imx/clk-imx8ulp.c
> +++ b/drivers/clk/imx/clk-imx8ulp.c
> @@ -275,14 +275,14 @@ static int imx8ulp_clk_cgc2_init(struct platform_device *pdev)
>  	clks[IMX8ULP_CLK_PLL4_PFD2_DIV2_GATE] = imx_clk_hw_gate_dis("pll4_pfd2_div2_gate", "pll4_pfd2", base + 0x60c, 15);
>  	clks[IMX8ULP_CLK_PLL4_PFD3_DIV1_GATE] = imx_clk_hw_gate_dis("pll4_pfd3_div1_gate", "pll4_pfd3", base + 0x60c, 23);
>  	clks[IMX8ULP_CLK_PLL4_PFD3_DIV2_GATE] = imx_clk_hw_gate_dis("pll4_pfd3_div2_gate", "pll4_pfd3", base + 0x60c, 31);
> -	clks[IMX8ULP_CLK_PLL4_PFD0_DIV1] = imx_clk_hw_divider("pll4_pfd0_div1", "pll4_pfd0_div1_gate", base + 0x608, 0, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD0_DIV2] = imx_clk_hw_divider("pll4_pfd0_div2", "pll4_pfd0_div2_gate", base + 0x608, 8, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD1_DIV1] = imx_clk_hw_divider("pll4_pfd1_div1", "pll4_pfd1_div1_gate", base + 0x608, 16, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD1_DIV2] = imx_clk_hw_divider("pll4_pfd1_div2", "pll4_pfd1_div2_gate", base + 0x608, 24, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD2_DIV1] = imx_clk_hw_divider("pll4_pfd2_div1", "pll4_pfd2_div1_gate", base + 0x60c, 0, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD2_DIV2] = imx_clk_hw_divider("pll4_pfd2_div2", "pll4_pfd2_div2_gate", base + 0x60c, 8, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD3_DIV1] = imx_clk_hw_divider("pll4_pfd3_div1", "pll4_pfd3_div1_gate", base + 0x60c, 16, 6);
> -	clks[IMX8ULP_CLK_PLL4_PFD3_DIV2] = imx_clk_hw_divider("pll4_pfd3_div2", "pll4_pfd3_div2_gate", base + 0x60c, 24, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD0_DIV1] = imx_clk_hw_divider_closest("pll4_pfd0_div1", "pll4_pfd0_div1_gate", base + 0x608, 0, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD0_DIV2] = imx_clk_hw_divider_closest("pll4_pfd0_div2", "pll4_pfd0_div2_gate", base + 0x608, 8, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD1_DIV1] = imx_clk_hw_divider_closest("pll4_pfd1_div1", "pll4_pfd1_div1_gate", base + 0x608, 16, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD1_DIV2] = imx_clk_hw_divider_closest("pll4_pfd1_div2", "pll4_pfd1_div2_gate", base + 0x608, 24, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD2_DIV1] = imx_clk_hw_divider_closest("pll4_pfd2_div1", "pll4_pfd2_div1_gate", base + 0x60c, 0, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD2_DIV2] = imx_clk_hw_divider_closest("pll4_pfd2_div2", "pll4_pfd2_div2_gate", base + 0x60c, 8, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD3_DIV1] = imx_clk_hw_divider_closest("pll4_pfd3_div1", "pll4_pfd3_div1_gate", base + 0x60c, 16, 6);
> +	clks[IMX8ULP_CLK_PLL4_PFD3_DIV2] = imx_clk_hw_divider_closest("pll4_pfd3_div2", "pll4_pfd3_div2_gate", base + 0x60c, 24, 6);
>  
>  	clks[IMX8ULP_CLK_CGC2_SOSC_DIV1_GATE] = imx_clk_hw_gate_dis("cgc2_sosc_div1_gate", "sosc", base + 0x108, 7);
>  	clks[IMX8ULP_CLK_CGC2_SOSC_DIV2_GATE] = imx_clk_hw_gate_dis("cgc2_sosc_div2_gate", "sosc", base + 0x108, 15);
> diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
> index bb105d6e5b39..ca1f75eb3197 100644
> --- a/drivers/clk/imx/clk.h
> +++ b/drivers/clk/imx/clk.h
> @@ -356,6 +356,15 @@ static inline struct clk_hw *imx_clk_hw_fixed_factor(const char *name,
>  			CLK_SET_RATE_PARENT, mult, div);
>  }
>  
> +static inline struct clk_hw *imx_clk_hw_divider_closest(const char *name,
> +						const char *parent,
> +						void __iomem *reg, u8 shift,
> +						u8 width)
> +{
> +	return clk_hw_register_divider(NULL, name, parent, 0,
> +				       reg, shift, width, CLK_DIVIDER_ROUND_CLOSEST, &imx_ccm_lock);
> +}
> +
>  static inline struct clk_hw *__imx_clk_hw_divider(const char *name,
>  						   const char *parent,
>  						   void __iomem *reg, u8 shift,
> -- 
> 2.37.1
>