linux-kernel - Re: [PATCH v2 5/6] PCI: fu740: Add SiFive FU740 PCIe host controller driver

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Message-ID: <YFQqpojmJyX0l6lx@rocinante>
Date:   Fri, 19 Mar 2021 05:37:58 +0100
From:   Krzysztof Wilczyński <kw@...ux.com>
To:     Greentime Hu <greentime.hu@...ive.com>
Cc:     paul.walmsley@...ive.com, hes@...ive.com, erik.danie@...ive.com,
        zong.li@...ive.com, bhelgaas@...gle.com, robh+dt@...nel.org,
        palmer@...belt.com, aou@...s.berkeley.edu, mturquette@...libre.com,
        sboyd@...nel.org, lorenzo.pieralisi@....com,
        p.zabel@...gutronix.de, alex.dewar90@...il.com,
        khilman@...libre.com, hayashi.kunihiko@...ionext.com,
        vidyas@...dia.com, jh80.chung@...sung.com,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, helgaas@...nel.org
Subject: Re: [PATCH v2 5/6] PCI: fu740: Add SiFive FU740 PCIe host controller
 driver

Hi,

[...]
> +static void fu740_phyregwrite(const uint8_t phy, const uint16_t addr,
> +			      const uint16_t wrdata, struct fu740_pcie *afp)
> +{
> +	struct device *dev = afp->pci.dev;
> +	void __iomem *phy_cr_para_addr;
> +	void __iomem *phy_cr_para_wr_data;
> +	void __iomem *phy_cr_para_wr_en;
> +	void __iomem *phy_cr_para_ack;
> +	int ret, val;
> +
> +	/* Setup */
> +	if (phy) {
> +		phy_cr_para_addr = afp->mgmt_base + PCIEX8MGMT_PHY1_CR_PARA_ADDR;
> +		phy_cr_para_wr_data = afp->mgmt_base + PCIEX8MGMT_PHY1_CR_PARA_WR_DATA;
> +		phy_cr_para_wr_en = afp->mgmt_base + PCIEX8MGMT_PHY1_CR_PARA_WR_EN;
> +		phy_cr_para_ack = afp->mgmt_base + PCIEX8MGMT_PHY1_CR_PARA_ACK;
> +	} else {
> +		phy_cr_para_addr = afp->mgmt_base + PCIEX8MGMT_PHY0_CR_PARA_ADDR;
> +		phy_cr_para_wr_data = afp->mgmt_base + PCIEX8MGMT_PHY0_CR_PARA_WR_DATA;
> +		phy_cr_para_wr_en = afp->mgmt_base + PCIEX8MGMT_PHY0_CR_PARA_WR_EN;
> +		phy_cr_para_ack = afp->mgmt_base + PCIEX8MGMT_PHY0_CR_PARA_ACK;
> +	}
> +
> +	writel_relaxed(addr, phy_cr_para_addr);
> +	writel_relaxed(wrdata, phy_cr_para_wr_data);
> +	writel_relaxed(1, phy_cr_para_wr_en);
> +
> +	/* Wait for wait_idle */
> +	ret = readl_poll_timeout(phy_cr_para_ack, val, val, 10, 5000);
> +	if (ret)
> +		dev_err(dev, "Wait for wait_ilde state failed!\n");

It would be "wait_idle" rather than "wait_idle".

[...]
> +	/* Wait for ~wait_idle */
> +	ret = readl_poll_timeout(phy_cr_para_ack, val, !val, 10, 5000);
> +	if (ret)
> +		dev_err(dev, "Wait for !wait_ilde state failed!\n");
[...]

Same as above, it would be "wait_idle" in the above.

> +static void fu740_pcie_ltssm_enable(struct device *dev)
> +{
> +	struct fu740_pcie *afp = dev_get_drvdata(dev);
> +
> +	/* Enable LTSSM */
> +	writel_relaxed(0x1, afp->mgmt_base + PCIEX8MGMT_APP_LTSSM_ENABLE);
> +}
> +
> +static int fu740_pcie_start_link(struct dw_pcie *pci)
> +{
> +	struct device *dev = pci->dev;
> +
> +	/* Start LTSSM. */

Nitpick.  No need for a dot in this comment to keep it consistent with
the comment in the function above this one.

> +static int fu740_pcie_host_init(struct pcie_port *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct fu740_pcie *afp = to_fu740_pcie(pci);
> +	struct device *dev = pci->dev;
> +	int ret;
> +
> +	/* Power on reset */
> +	fu740_pcie_drive_perstn(afp);
> +
> +	/* Enable pcieauxclk */
> +	ret = clk_prepare_enable(afp->pcie_aux);
> +	if (ret)
> +		dev_err(dev, "unable to enable pcie_aux clock\n");
> +
> +	/*
> +	 * Assert hold_phy_rst (hold the controller LTSSM in reset after
> +	 * power_up_rst_n for register programming with cr_para)
> +	 */
> +	writel_relaxed(0x1, afp->mgmt_base + PCIEX8MGMT_APP_HOLD_PHY_RST);
> +
> +	/* Deassert power_up_rst_n */
> +	ret = reset_control_deassert(afp->rst);
> +	if (ret)
> +		dev_err(dev, "unable to deassert pcie_power_up_rst_n\n");
> +
> +	fu740_pcie_init_phy(afp);
> +
> +	/* Disable pcieauxclk */
> +	clk_disable_unprepare(afp->pcie_aux);
> +	/* Clear hold_phy_rst */
> +	writel_relaxed(0x0, afp->mgmt_base + PCIEX8MGMT_APP_HOLD_PHY_RST);
> +	/* Enable pcieauxclk */
> +	ret = clk_prepare_enable(afp->pcie_aux);
> +	/* Set RC mode */
> +	writel_relaxed(0x4, afp->mgmt_base + PCIEX8MGMT_DEVICE_TYPE);
> +
> +	return 0;
> +}
[...]

It seems that the error handling is somewhat broken in the above
function, especially when you look at how the "ret" variables does not
seem to be used for anything once there was an error.

Krzysztof