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SubjectRe: [PATCH v9 8/8] PCI: imx6: Add compliance tests mode support
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Am Freitag, dem 06.05.2022 um 09:47 +0800 schrieb Richard Zhu:
> Refer to the Chapter 3.2 System Board Signal Quality of PCI Express
> Architecture PHY Test Specification Revision 2.0.
>
> Signal quality tests (for example: jitter, differential eye opening and
> so on) can be executed with devices in the polling.compliance state.
>
> To let the device support polling.compliance state, the clocks and powers
> shouldn't be turned off when the probe of device driver fails.
>
> Based on CLB (Compliance Load Board) Test Fixture and so on test
> equipments, the PHY link would be down during the compliance tests.
> Refer to this scenario, add the i.MX PCIe compliance tests mode enable
> support, and keep the clocks and powers on, and finish the driver probe
> without error return.
>
> Use the "pci_imx6.compliance=1" in kernel command line to enable the
> compliance tests mode.
>
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
> drivers/pci/controller/dwc/pci-imx6.c | 39 ++++++++++++++++++---------
> 1 file changed, 27 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index f0ffd9011975..f78b59822626 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -146,6 +146,10 @@ struct imx6_pcie {
> #define PHY_RX_OVRD_IN_LO_RX_DATA_EN BIT(5)
> #define PHY_RX_OVRD_IN_LO_RX_PLL_EN BIT(3)
>
> +static bool imx6_pcie_cmp_mode;
> +module_param_named(compliance, imx6_pcie_cmp_mode, bool, 0644);
> +MODULE_PARM_DESC(compliance, "i.MX PCIe compliance test mode (1=compliance test mode enabled)");
> +
> static int pcie_phy_poll_ack(struct imx6_pcie *imx6_pcie, bool exp_val)
> {
> struct dw_pcie *pci = imx6_pcie->pci;
> @@ -826,10 +830,12 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
> * started in Gen2 mode, there is a possibility the devices on the
> * bus will not be detected at all. This happens with PCIe switches.
> */
> - tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> - tmp &= ~PCI_EXP_LNKCAP_SLS;
> - tmp |= PCI_EXP_LNKCAP_SLS_2_5GB;
> - dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
> + if (!imx6_pcie_cmp_mode) {
> + tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> + tmp &= ~PCI_EXP_LNKCAP_SLS;
> + tmp |= PCI_EXP_LNKCAP_SLS_2_5GB;
> + dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
> + }
>
> /* Start LTSSM. */
> imx6_pcie_ltssm_enable(dev);
> @@ -887,14 +893,16 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
> dev_dbg(dev, "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n",
> dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
> dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
> - imx6_pcie_reset_phy(imx6_pcie);
> - imx6_pcie_clk_disable(imx6_pcie);
> - if (imx6_pcie->phy != NULL) {
> - phy_power_off(imx6_pcie->phy);
> - phy_exit(imx6_pcie->phy);
> + if (!imx6_pcie_cmp_mode) {
> + imx6_pcie_reset_phy(imx6_pcie);
> + imx6_pcie_clk_disable(imx6_pcie);
> + if (imx6_pcie->phy != NULL) {
> + phy_power_off(imx6_pcie->phy);
> + phy_exit(imx6_pcie->phy);
> + }
> + if (imx6_pcie->vpcie)
> + regulator_disable(imx6_pcie->vpcie);
> }
> - if (imx6_pcie->vpcie)
> - regulator_disable(imx6_pcie->vpcie);
> return ret;
> }
>
> @@ -1289,8 +1297,15 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> return ret;
>
> ret = dw_pcie_host_init(&pci->pp);
> - if (ret < 0)
> + if (ret < 0) {
> + if (imx6_pcie_cmp_mode) {
> + dev_info(dev, "driver loaded with compliance test mode enabled\n");
> + ret = 0;
> + } else {
> + dev_err(dev, "unable to add PCIe port\n");
> + }
> return ret;
> + }

If you drop the error return from imx6_pcie_start_link, like I
suggested in patch 6/8, you don't need this block as dw_pcie_host_init
will succeed even if the link is down or in compliance test mode.

Regards,
Lucas

>
> if (pci_msi_enabled()) {
> u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);


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