linux-kernel - Re: [PATCH V7 2/5] phy: freescale: fsl-samsung-hdmi: Simplify REG21_PMS_S

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Message-ID: <ZuEpQLcDQ8pgMTUB@atmark-techno.com>
Date: Wed, 11 Sep 2024 14:23:12 +0900
From: Dominique Martinet <dominique.martinet@...ark-techno.com>
To: Adam Ford <aford173@...il.com>
Cc: linux-phy@...ts.infradead.org, linux-imx@....com, festevam@...il.com,
	frieder.schrempf@...tron.de, aford@...conembedded.com,
	Sandor.yu@....com, Marco Felsch <m.felsch@...gutronix.de>,
	Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Lucas Stach <l.stach@...gutronix.de>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V7 2/5] phy: freescale: fsl-samsung-hdmi: Simplify
 REG21_PMS_S_MASK lookup

Adam Ford wrote on Tue, Sep 10, 2024 at 08:28:08PM -0500:
> The value of 'S' is writen to two places, PHY_REG3[7:4] and
> PHY_REG21[3:0].  There is a lookup table which contains
> the value of PHY_REG3.  Rather than using a switch statement
> based on the pixel clock to search for the value of 'S' again,
> just shift the contents of PHY_REG3[7:4] >> 4 and place the value
> in PHY_REG21[3:0].  Doing this can eliminate an entire function.
> 
> Signed-off-by: Adam Ford <aford173@...il.com>
> Reviewed-by: Marco Felsch <m.felsch@...gutronix.de>
> Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> Tested-by: Frieder Schrempf <frieder.schrempf@...tron.de>

Reviewed-by: Dominique Martinet <dominique.martinet@...ark-techno.com>
Tested-by: Dominique Martinet <dominique.martinet@...ark-techno.com>

> ---
>  drivers/phy/freescale/phy-fsl-samsung-hdmi.c | 39 ++------------------
>  1 file changed, 4 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/phy/freescale/phy-fsl-samsung-hdmi.c b/drivers/phy/freescale/phy-fsl-samsung-hdmi.c
> index acea7008aefc..4f6874226f9a 100644
> --- a/drivers/phy/freescale/phy-fsl-samsung-hdmi.c
> +++ b/drivers/phy/freescale/phy-fsl-samsung-hdmi.c
> @@ -364,40 +364,6 @@ to_fsl_samsung_hdmi_phy(struct clk_hw *hw)
>  	return container_of(hw, struct fsl_samsung_hdmi_phy, hw);
>  }
>  
> -static void
> -fsl_samsung_hdmi_phy_configure_pixclk(struct fsl_samsung_hdmi_phy *phy,
> -				      const struct phy_config *cfg)
> -{
> -	u8 div = 0x1;
> -
> -	switch (cfg->pixclk) {
> -	case  22250000 ...  33750000:
> -		div = 0xf;
> -		break;
> -	case  35000000 ...  40000000:
> -		div = 0xb;
> -		break;
> -	case  43200000 ...  47500000:
> -		div = 0x9;
> -		break;
> -	case  50349650 ...  63500000:
> -		div = 0x7;
> -		break;
> -	case  67500000 ...  90000000:
> -		div = 0x5;
> -		break;
> -	case  94000000 ... 148500000:
> -		div = 0x3;
> -		break;
> -	case 154000000 ... 297000000:
> -		div = 0x1;
> -		break;
> -	}
> -
> -	writeb(REG21_SEL_TX_CK_INV | FIELD_PREP(REG21_PMS_S_MASK, div),
> -	       phy->regs + PHY_REG(21));
> -}
> -
>  static void
>  fsl_samsung_hdmi_phy_configure_pll_lock_det(struct fsl_samsung_hdmi_phy *phy,
>  					    const struct phy_config *cfg)
> @@ -466,7 +432,10 @@ static int fsl_samsung_hdmi_phy_configure(struct fsl_samsung_hdmi_phy *phy,
>  	for (i = 0; i < PHY_PLL_DIV_REGS_NUM; i++)
>  		writeb(cfg->pll_div_regs[i], phy->regs + PHY_REG(2) + i * 4);
>  
> -	fsl_samsung_hdmi_phy_configure_pixclk(phy, cfg);
> +	/* High nibble of pll_div_regs[1] contains S which also gets written to REG21 */
> +	writeb(REG21_SEL_TX_CK_INV | FIELD_PREP(REG21_PMS_S_MASK,
> +	       cfg->pll_div_regs[1] >> 4), phy->regs + PHY_REG(21));
> +
>  	fsl_samsung_hdmi_phy_configure_pll_lock_det(phy, cfg);
>  
>  	writeb(REG33_FIX_DA | REG33_MODE_SET_DONE, phy->regs + PHY_REG(33));