linux-kernel - Re: [PATCH v2 2/2] phy: socionext: Add UniPhier AHCI PHY driver support

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Message-ID: <9f358850-eb2a-769c-be57-866d77183a7f@socionext.com>
Date:   Tue, 14 Jul 2020 18:10:50 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] phy: socionext: Add UniPhier AHCI PHY driver
 support

Hi Vinod,

On 2020/07/13 14:05, Vinod Koul wrote:
> On 30-06-20, 17:59, Kunihiko Hayashi wrote:
> 
>> +++ b/drivers/phy/socionext/phy-uniphier-ahci.c
>> @@ -0,0 +1,335 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * phy-uniphier-ahci.c - PHY driver for UniPhier AHCI controller
>> + * Copyright 2016-2018, Socionext Inc.
> 
> we are in 2020 now!

Oops, I'll adjust it.

>> +static int uniphier_ahciphy_pxs2_power_on(struct uniphier_ahciphy_priv *priv)
>> +{
>> +	int ret;
>> +	u32 val;
>> +
>> +	/* enable reference clock for PHY */
>> +	val = readl(priv->base + CKCTRL);
>> +	val |= CKCTRL_REF_SSP_EN;
>> +	writel(val, priv->base + CKCTRL);
>> +
>> +	/* release port reset */
>> +	val = readl(priv->base + CKCTRL);
>> +	val &= ~CKCTRL_P0_RESET;
>> +	writel(val, priv->base + CKCTRL);
>> +
>> +	/* wait until PLL is ready */
>> +	if (priv->data->is_ready_high)
>> +		ret = readl_poll_timeout(priv->base + CKCTRL, val,
>> +					 (val & CKCTRL_P0_READY), 200, 400);
>> +	else
>> +		ret = readl_poll_timeout(priv->base + CKCTRL, val,
>> +					 !(val & CKCTRL_P0_READY), 200, 400);
>> +	if (ret) {
>> +		dev_err(priv->dev, "Failed to check whether PHY PLL is ready\n");
>> +		goto out_disable_clock;
>> +	}
>> +
>> +	return 0;
>> +
>> +out_disable_clock:
>> +	/* assert port reset */
>> +	val = readl(priv->base + CKCTRL);
>> +	val |= CKCTRL_P0_RESET;
>> +	writel(val, priv->base + CKCTRL);
>> +
>> +	/* disable reference clock for PHY */
>> +	val = readl(priv->base + CKCTRL);
>> +	val &= ~CKCTRL_REF_SSP_EN;
>> +	writel(val, priv->base + CKCTRL);
> 
> this seems to be repeated patter, why not add a modifyl() helper here..

Hmm, I try to add helpers for modifying P0_RESET and REF_SSP_EN bits.

> 
>> +static int uniphier_ahciphy_pxs3_init(struct uniphier_ahciphy_priv *priv)
>> +{
>> +	int i;
>> +	u32 val;
>> +
>> +	/* setup port parameter */
>> +	val = readl(priv->base + TXCTRL0);
>> +	val &= ~TXCTRL0_AMP_G3_MASK;
>> +	val |= FIELD_PREP(TXCTRL0_AMP_G3_MASK, 0x73);
>> +	val &= ~TXCTRL0_AMP_G2_MASK;
>> +	val |= FIELD_PREP(TXCTRL0_AMP_G2_MASK, 0x46);
>> +	val &= ~TXCTRL0_AMP_G1_MASK;
>> +	val |= FIELD_PREP(TXCTRL0_AMP_G1_MASK, 0x42);
>> +	writel(val, priv->base + TXCTRL0);
>> +
>> +	val = readl(priv->base + TXCTRL1);
>> +	val &= ~TXCTRL1_DEEMPH_G3_MASK;
>> +	val |= FIELD_PREP(TXCTRL1_DEEMPH_G3_MASK, 0x23);
>> +	val &= ~TXCTRL1_DEEMPH_G2_MASK;
>> +	val |= FIELD_PREP(TXCTRL1_DEEMPH_G2_MASK, 0x05);
>> +	val &= ~TXCTRL1_DEEMPH_G1_MASK;
>> +	val |= FIELD_PREP(TXCTRL1_DEEMPH_G1_MASK, 0x05);
>> +
>> +	val = readl(priv->base + RXCTRL);
>> +	val &= ~RXCTRL_LOS_LVL_MASK;
>> +	val |= FIELD_PREP(RXCTRL_LOS_LVL_MASK, 0x9);
>> +	val &= ~RXCTRL_LOS_BIAS_MASK;
>> +	val |= FIELD_PREP(RXCTRL_LOS_BIAS_MASK, 0x2);
>> +	val &= ~RXCTRL_RX_EQ_MASK;
>> +	val |= FIELD_PREP(RXCTRL_RX_EQ_MASK, 0x1);
>> +
>> +	/* dummy read 25 times */
> 
> why?

According to the specification document,
these 25 read accesses make a wait time for the phy to stablize.
I'll add the reason as comment.

> 
>> +static int uniphier_ahciphy_init(struct phy *phy)
>> +{
>> +	struct uniphier_ahciphy_priv *priv = phy_get_drvdata(phy);
>> +	int ret;
>> +
>> +	ret = clk_prepare_enable(priv->clk_parent);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = reset_control_deassert(priv->rst_parent);
>> +	if (ret)
>> +		goto out_clk_disable;
>> +
>> +	if (priv->data->init) {
>> +		ret = priv->data->init(priv);
>> +		if (ret)
>> +			goto out_rst_assert;
>> +	}
>> +
>> +	return ret;
> 
> return 0?

Yes, I'll fix it.

> 
>> +static const struct uniphier_ahciphy_soc_data uniphier_pxs2_data = {
>> +	.init = NULL,
> 
> Isn't this superfluous ?

Indeed, this can be removed.

Thank you,

---
Best Regards
Kunihiko Hayashi