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Message-ID: <YY23MeAa0U/r4lbO@rocinante>
Date: Fri, 12 Nov 2021 01:37:05 +0100
From: Krzysztof Wilczyński <kw@...ux.com>
To: Zhiqiang Hou <Zhiqiang.Hou@....com>
Cc: linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
lorenzo.pieralisi@....com, robh+dt@...nel.org, bhelgaas@...gle.com,
shawnguo@...nel.org, leoyang.li@....com,
gustavo.pimentel@...opsys.com, minghuan.Lian@....com,
mingkai.hu@....com, roy.zang@....com
Subject: Re: [PATCHv5 6/6] PCI: layerscape: Add power management support
Hi,
[...]
> +/* PF Message Command Register */
> +#define LS_PCIE_PF_MCR 0x2c
> +#define PF_MCR_PTOMR BIT(0)
> +#define PF_MCR_EXL2S BIT(1)
> +
> +/* LS1021A PEXn PM Write Control Register */
> +#define SCFG_PEXPMWRCR(idx) (0x5c + (idx) * 0x64)
> +#define PMXMTTURNOFF BIT(31)
> +#define SCFG_PEXSFTRSTCR 0x190
> +#define PEXSR(idx) BIT(idx)
> +
> +/* LS1043A PEX PME control register */
> +#define SCFG_PEXPMECR 0x144
> +#define PEXPME(idx) BIT(31 - (idx) * 4)
> +
> +/* LS1043A PEX LUT debug register */
> +#define LS_PCIE_LDBG 0x7fc
> +#define LDBG_SR BIT(30)
> +#define LDBG_WE BIT(31)
A small nitpick: a consistent capitalisation of "control" and "debug", and
"register" in the comments above.
[...]
> +static void ls_pcie_lut_writel(struct ls_pcie *pcie, u32 off, u32 val)
> +{
> + if (pcie->big_endian)
> + return iowrite32be(val, pcie->lut_base + off);
> +
> + return iowrite32(val, pcie->lut_base + off);
> +
> +}
Surplus newline above after the return statement.
[...]
> +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> +{
> + if (pcie->big_endian)
> + return iowrite32be(val, pcie->pf_base + off);
> +
> + return iowrite32(val, pcie->pf_base + off);
> +
> +}
Surplus newline above after the return statement.
[...]
> +static void ls_pcie_send_turnoff_msg(struct ls_pcie *pcie)
> +{
> + u32 val;
> + int ret;
> +
> + val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> + val |= PF_MCR_PTOMR;
> + ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> +
> + ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> + val, !(val & PF_MCR_PTOMR), 100, 10000);
> + if (ret)
> + dev_info(pcie->pci->dev, "poll turn off message timeout\n");
> +}
Would this dev_info() be more of a warning or an error? A timeout is
potentially a problem, correct?
[...]
> +static void ls1021a_pcie_send_turnoff_msg(struct ls_pcie *pcie)
> +{
> + u32 val;
> +
> + if (!pcie->scfg) {
> + dev_dbg(pcie->pci->dev, "SYSCFG is NULL\n");
> + return;
> + }
> +
> + /* Send Turn_off message */
> + regmap_read(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), &val);
> + val |= PMXMTTURNOFF;
> + regmap_write(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), val);
> +
> + mdelay(10);
We often, customary, document why a particular mdelay() is needed. You
also did this in other part of the code, so perhaps adding a note here (and
everywhere else) would be nice for keeping the consistency.
[...]
> +static void ls_pcie_exit_from_l2(struct ls_pcie *pcie)
> +{
> + u32 val;
> + int ret;
> +
> + val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> + val |= PF_MCR_EXL2S;
> + ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> +
> + ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> + val, !(val & PF_MCR_EXL2S), 100, 10000);
> + if (ret)
> + dev_info(pcie->pci->dev, "poll exit L2 state timeout\n");
> +}
Similarly to the question above: is this timeout something more severe and
would warrant a warning or an error here instead?
[...]
> +static void ls1021a_pcie_exit_from_l2(struct ls_pcie *pcie)
> +{
> + u32 val;
> +
> + regmap_read(pcie->scfg, SCFG_PEXSFTRSTCR, &val);
> + val |= PEXSR(pcie->index);
> + regmap_write(pcie->scfg, SCFG_PEXSFTRSTCR, val);
> +
> + regmap_read(pcie->scfg, SCFG_PEXSFTRSTCR, &val);
> + val &= ~PEXSR(pcie->index);
> + regmap_write(pcie->scfg, SCFG_PEXSFTRSTCR, val);
> +
> + mdelay(1);
Aside of documenting this mdelay() here, if possible, would 1 be enough?
Everywhere else you seem to use 10 consistently.
> +
> + ls_pcie_retrain_link(pcie);
> +}
> +static void ls1043a_pcie_exit_from_l2(struct ls_pcie *pcie)
Missing newline above to separate code blocks.
> +{
> + u32 val;
> +
> + val = ls_pcie_lut_readl(pcie, LS_PCIE_LDBG);
> + val |= LDBG_WE;
> + ls_pcie_lut_writel(pcie, LS_PCIE_LDBG, val);
> +
> + val = ls_pcie_lut_readl(pcie, LS_PCIE_LDBG);
> + val |= LDBG_SR;
> + ls_pcie_lut_writel(pcie, LS_PCIE_LDBG, val);
> +
> + val = ls_pcie_lut_readl(pcie, LS_PCIE_LDBG);
> + val &= ~LDBG_SR;
> + ls_pcie_lut_writel(pcie, LS_PCIE_LDBG, val);
> +
> + val = ls_pcie_lut_readl(pcie, LS_PCIE_LDBG);
> + val &= ~LDBG_WE;
> + ls_pcie_lut_writel(pcie, LS_PCIE_LDBG, val);
> +
> + mdelay(1);
See comment above.
[...]
> +static int ls1021a_pcie_pm_init(struct ls_pcie *pcie)
> +{
> + struct device *dev = pcie->pci->dev;
> + u32 index[2];
> + int ret;
> +
> + pcie->scfg = syscon_regmap_lookup_by_phandle(dev->of_node,
> + "fsl,pcie-scfg");
> + if (IS_ERR(pcie->scfg)) {
> + ret = PTR_ERR(pcie->scfg);
> + dev_err(dev, "No syscfg phandle specified\n");
> + pcie->scfg = NULL;
> + return ret;
> + }
> +
> + ret = of_property_read_u32_array(dev->of_node, "fsl,pcie-scfg",
> + index, 2);
> + if (ret) {
> + pcie->scfg = NULL;
> + return ret;
> + }
> +
> + pcie->index = index[1];
> +
> + return 0;
> +}
Just an idea: what about using goto for error handling?
(...)
if (IS_ERR(pcie->scfg)) {
ret = PTR_ERR(pcie->scfg);
dev_err(dev, "No syscfg phandle specified\n");
goto error;
}
ret = of_property_read_u32_array(dev->of_node, "fsl,pcie-scfg",
index, 2);
if (ret)
goto error;
pcie->index = index[1];
return 0;
error:
pcie->scfg = NULL;
return ret;
}
Not necessarily better or worse compared with your version, so it would be
more of a matter of personal preference here.
> +static int ls_pcie_suspend_noirq(struct device *dev)
> +{
> + struct ls_pcie *pcie = dev_get_drvdata(dev);
> + struct dw_pcie *pci = pcie->pci;
> + u32 val;
> + int ret;
> +
> + if (!ls_pcie_pm_check(pcie))
> + return 0;
> +
> + pcie->drvdata->pm_ops->send_turn_off_message(pcie);
> +
> + /* 10ms timeout to check L2 ready */
> + ret = readl_poll_timeout(pci->dbi_base + PCIE_PORT_DEBUG0,
> + val, LS_PCIE_IS_L2(val), 100, 10000);
> + if (ret) {
> + dev_err(dev, "PCIe link enter L2 timeout! ltssm = 0x%x\n", val);
> + return ret;
> + }
The error message above could be improve to be more like an error stating
that something failed and such, as currently it looks like a debug message,
unless it was intended as such.
[...]
> +static int ls_pcie_resume_noirq(struct device *dev)
> +{
> + struct ls_pcie *pcie = dev_get_drvdata(dev);
> + struct dw_pcie *pci = pcie->pci;
> + int ret;
> +
> + if (!ls_pcie_pm_check(pcie))
> + return 0;
> +
> + ls_pcie_set_dstate(pcie, 0x0);
> +
> + pcie->drvdata->pm_ops->exit_from_l2(pcie);
> +
> + dw_pcie_setup_rc(&pci->pp);
> +
> + /* delay 10 ms to access EP */
> + mdelay(10);
> +
> + ret = ls_pcie_host_init(&pci->pp);
> + if (ret) {
> + dev_err(dev, "ls_pcie_host_init failed! ret = 0x%x\n", ret);
> + return ret;
> + }
A small nitpick: error messages that are directed at end users should have
a little more context than just the function name.
Krzysztof
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