linux-kernel - Re: [PATCH v10 14/18] phy: sun4i-usb: Introduce port2 SIDDQ quirk

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Message-ID: <14105ae3-4314-3463-8b07-ccd6106cf681@sholland.org>
Date:   Tue, 22 Feb 2022 21:57:07 -0600
From:   Samuel Holland <samuel@...lland.org>
To:     Andre Przywara <andre.przywara@....com>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>
Cc:     Rob Herring <robh@...nel.org>, Ondrej Jirman <megous@...ous.com>,
        Icenowy Zheng <icenowy@...c.io>,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>, linux-phy@...ts.infradead.org
Subject: Re: [PATCH v10 14/18] phy: sun4i-usb: Introduce port2 SIDDQ quirk

On 2/11/22 6:26 AM, Andre Przywara wrote:
> At least the Allwinner H616 SoC requires a weird quirk to make most
> USB PHYs work: Only port2 works out of the box, but all other ports
> need some help from this port2 to work correctly: The CLK_BUS_PHY2 and
> RST_USB_PHY2 clock and reset need to be enabled, and the SIDDQ bit in
> the PMU PHY control register needs to be cleared. For this register to
> be accessible, CLK_BUS_ECHI2 needs to be ungated. Don't ask ....
> 
> Instead of disguising this as some generic feature, do exactly that
> in our PHY init:
> If the quirk bit is set, and we initialise a PHY other than PHY2, ungate
> this one special clock, and clear the SIDDQ bit. We can pull in the
> other required clocks via the DT.
> 
> Signed-off-by: Andre Przywara <andre.przywara@....com>
> ---
>  drivers/phy/allwinner/phy-sun4i-usb.c | 59 +++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/drivers/phy/allwinner/phy-sun4i-usb.c b/drivers/phy/allwinner/phy-sun4i-usb.c
> index 126ef74d013c..316ef5fca831 100644
> --- a/drivers/phy/allwinner/phy-sun4i-usb.c
> +++ b/drivers/phy/allwinner/phy-sun4i-usb.c
> @@ -120,6 +120,7 @@ struct sun4i_usb_phy_cfg {
>  	u8 phyctl_offset;
>  	bool dedicated_clocks;
>  	bool phy0_dual_route;
> +	bool needs_phy2_siddq;
>  	int missing_phys;
>  };
>  
> @@ -289,6 +290,50 @@ static int sun4i_usb_phy_init(struct phy *_phy)
>  		return ret;
>  	}
>  
> +	/* Some PHYs on some SoCs need the help of PHY2 to work. */
> +	if (data->cfg->needs_phy2_siddq && phy->index != 2) {
> +		struct sun4i_usb_phy *phy2 = &data->phys[2];
> +
> +		ret = clk_prepare_enable(phy2->clk);
> +		if (ret) {
> +			reset_control_assert(phy->reset);
> +			clk_disable_unprepare(phy->clk2);
> +			clk_disable_unprepare(phy->clk);
> +			return ret;
> +		}
> +
> +		ret = reset_control_deassert(phy2->reset);
> +		if (ret) {
> +			clk_disable_unprepare(phy2->clk);
> +			reset_control_assert(phy->reset);
> +			clk_disable_unprepare(phy->clk2);
> +			clk_disable_unprepare(phy->clk);
> +			return ret;
> +		}
> +
> +		/*
> +		 * This extra clock is just needed to access the
> +		 * REG_HCI_PHY_CTL PMU register for PHY2.
> +		 */
> +		ret = clk_prepare_enable(phy2->clk2);
> +		if (ret) {
> +			reset_control_assert(phy2->reset);
> +			clk_disable_unprepare(phy2->clk);
> +			reset_control_assert(phy->reset);
> +			clk_disable_unprepare(phy->clk2);
> +			clk_disable_unprepare(phy->clk);

This is quite a lot of duplication. Please consider using goto for the error path.

> +			return ret;
> +		}
> +
> +		if (phy2->pmu && data->cfg->hci_phy_ctl_clear) {
> +			val = readl(phy2->pmu + REG_HCI_PHY_CTL);
> +			val &= ~data->cfg->hci_phy_ctl_clear;
> +			writel(val, phy2->pmu + REG_HCI_PHY_CTL);
> +		}
> +
> +		clk_disable_unprepare(phy->clk2);
> +	}
> +
>  	if (phy->pmu && data->cfg->hci_phy_ctl_clear) {
>  		val = readl(phy->pmu + REG_HCI_PHY_CTL);
>  		val &= ~data->cfg->hci_phy_ctl_clear;
> @@ -354,6 +399,13 @@ static int sun4i_usb_phy_exit(struct phy *_phy)
>  		data->phy0_init = false;
>  	}
>  
> +	if (data->cfg->needs_phy2_siddq && phy->index != 2) {
> +		struct sun4i_usb_phy *phy2 = &data->phys[2];
> +
> +		clk_disable_unprepare(phy2->clk);
> +		reset_control_assert(phy2->reset);
> +	}
> +
>  	sun4i_usb_phy_passby(phy, 0);
>  	reset_control_assert(phy->reset);
>  	clk_disable_unprepare(phy->clk2);
> @@ -785,6 +837,13 @@ static int sun4i_usb_phy_probe(struct platform_device *pdev)
>  				dev_err(dev, "failed to get clock %s\n", name);
>  				return PTR_ERR(phy->clk2);
>  			}
> +		} else {
> +			snprintf(name, sizeof(name), "pmu%d_clk", i);
> +			phy->clk2 = devm_clk_get_optional(dev, name);

This clock is not documented anywhere in the binding.

Regards,
Samuel

> +			if (IS_ERR(phy->clk2)) {
> +				dev_err(dev, "failed to get clock %s\n", name);
> +				return PTR_ERR(phy->clk2);
> +			}
>  		}
>  
>  		snprintf(name, sizeof(name), "usb%d_reset", i);
>