linux-kernel - Re: [PATCH v2 2/3] phy: phy-mtk-tphy: add configurable parameters for slew rate calibrate

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Date:   Wed, 14 Mar 2018 00:21:20 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Kishon Vijay Abraham I <kishon@...com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Ryder Lee <ryder.lee@...iatek.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-usb@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/3] phy: phy-mtk-tphy: add configurable parameters for
 slew rate calibrate



On 03/12/2018 06:25 AM, Chunfeng Yun wrote:
> There are two parameters, ref_clk and coefficient, for U2 slew rate
> calibrate which may vary on different SoCs, here allow them to be
> configurable
> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>

Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>


> ---
>  drivers/phy/mediatek/phy-mtk-tphy.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/phy/mediatek/phy-mtk-tphy.c b/drivers/phy/mediatek/phy-mtk-tphy.c
> index 6073c25..38c281b 100644
> --- a/drivers/phy/mediatek/phy-mtk-tphy.c
> +++ b/drivers/phy/mediatek/phy-mtk-tphy.c
> @@ -306,6 +306,8 @@ struct mtk_tphy {
>  	const struct mtk_phy_pdata *pdata;
>  	struct mtk_phy_instance **phys;
>  	int nphys;
> +	int src_ref_clk; /* MHZ, reference clock for slew rate calibrate */
> +	int src_coef; /* coefficient for slew rate calibrate */
>  };
>  
>  static void hs_slew_rate_calibrate(struct mtk_tphy *tphy,
> @@ -360,16 +362,17 @@ static void hs_slew_rate_calibrate(struct mtk_tphy *tphy,
>  	writel(tmp, fmreg + U3P_U2FREQ_FMMONR1);
>  
>  	if (fm_out) {
> -		/* ( 1024 / FM_OUT ) x reference clock frequency x 0.028 */
> -		tmp = U3P_FM_DET_CYCLE_CNT * U3P_REF_CLK * U3P_SLEW_RATE_COEF;
> -		tmp /= fm_out;
> +		/* ( 1024 / FM_OUT ) x reference clock frequency x coef */
> +		tmp = tphy->src_ref_clk * tphy->src_coef;
> +		tmp = (tmp * U3P_FM_DET_CYCLE_CNT) / fm_out;
>  		calibration_val = DIV_ROUND_CLOSEST(tmp, U3P_SR_COEF_DIVISOR);
>  	} else {
>  		/* if FM detection fail, set default value */
>  		calibration_val = 4;
>  	}
> -	dev_dbg(tphy->dev, "phy:%d, fm_out:%d, calib:%d\n",
> -		instance->index, fm_out, calibration_val);
> +	dev_dbg(tphy->dev, "phy:%d, fm_out:%d, calib:%d (clk:%d, coef:%d)\n",
> +		instance->index, fm_out, calibration_val,
> +		tphy->src_ref_clk, tphy->src_coef);
>  
>  	/* set HS slew rate */
>  	tmp = readl(com + U3P_USBPHYACR5);
> @@ -1041,6 +1044,13 @@ static int mtk_tphy_probe(struct platform_device *pdev)
>  		tphy->u3phya_ref = NULL;
>  	}
>  
> +	tphy->src_ref_clk = U3P_REF_CLK;
> +	tphy->src_coef = U3P_SLEW_RATE_COEF;
> +	/* update parameters of slew rate calibrate if exist */
> +	device_property_read_u32(dev, "mediatek,src-ref-clk-mhz",
> +		&tphy->src_ref_clk);
> +	device_property_read_u32(dev, "mediatek,src-coef", &tphy->src_coef);
> +
>  	port = 0;
>  	for_each_child_of_node(np, child_np) {
>  		struct mtk_phy_instance *instance;
>