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Message-ID: <20180828100758.GA27217@e107981-ln.cambridge.arm.com>
Date: Tue, 28 Aug 2018 11:07:58 +0100
From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To: Leonard Crestez <leonard.crestez@....com>
Cc: Lucas Stach <l.stach@...gutronix.de>,
Andrey Smirnov <andrew.smirnov@...il.com>,
Richard Zhu <hongxing.zhu@....com>,
Anson Huang <Anson.Huang@....com>,
Philipp Zabel <p.zabel@...gutronix.de>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Jingoo Han <jingoohan1@...il.com>,
Joao Pinto <Joao.Pinto@...opsys.com>,
Fabio Estevam <fabio.estevam@....com>,
Dong Aisheng <aisheng.dong@....com>, linux-imx@....com,
kernel@...gutronix.de, linux-pci@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND] PCI: imx: Initial imx7d pm support
On Mon, Aug 27, 2018 at 02:28:37PM +0300, Leonard Crestez wrote:
> On imx7d the pcie-phy power domain is turned off in suspend and this can
> make the system hang after resume when attempting any read from PCI.
>
> Fix this by adding minimal suspend/resume code from the nxp internal
> tree. This will prepare for powering down on suspend and reset the block
> on resume.
>
> Code is only for imx7d but a very similar sequence can be used for
> other socs.
>
> The original author is mostly Richard Zhu <hongxing.zhu@....com>, this
> patch adjusts the code to the upstream imx7d implemention using reset
> controls and power domains.
I will add a Suggested-by: replacing this paragraph, it is always better
to add proper tags rather than credit hidden in commit logs messages.
> Signed-off-by: Leonard Crestez <leonard.crestez@....com>
> Reviewed-by: Lucas Stach <l.stach@...gutronix.de>
> ---
> drivers/pci/controller/dwc/pci-imx6.c | 97 +++++++++++++++++++++++++--
> 1 file changed, 92 insertions(+), 5 deletions(-)
>
> Resending after RC1 as suggested here: https://lkml.org/lkml/2018/8/8/496
>
> This was initially sent together with a dts fix, that was already
> accepted by Shawn: https://lkml.org/lkml/2018/8/21/529
>
> Some dependencies in this area are complicated but as far as I know
> including this patch without others should not break anything that was
> not already broken. Since this is a patch for something that has never
> worked before it should be treated as a feature not a bugfix.
Ok, so I consider this v4.20 material, please shout if it has to be
sent as a fix, I do not think so given what we discussed above.
Lorenzo
> I have a few other patches for imx pci but it's better to deal with them
> separately. This initial patch adding suspend support is useful by
> itself.
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 4a9a673b4777..65b6d1015723 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -540,10 +540,28 @@ static int imx6_pcie_wait_for_speed_change(struct imx6_pcie *imx6_pcie)
>
> dev_err(dev, "Speed change timeout\n");
> return -EINVAL;
> }
>
> +static void imx6_pcie_ltssm_enable(struct device *dev)
> +{
> + struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> +
> + switch (imx6_pcie->variant) {
> + case IMX6Q:
> + case IMX6SX:
> + case IMX6QP:
> + regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> + IMX6Q_GPR12_PCIE_CTL_2,
> + IMX6Q_GPR12_PCIE_CTL_2);
> + break;
> + case IMX7D:
> + reset_control_deassert(imx6_pcie->apps_reset);
> + break;
> + }
> +}
> +
> static int imx6_pcie_establish_link(struct imx6_pcie *imx6_pcie)
> {
> struct dw_pcie *pci = imx6_pcie->pci;
> struct device *dev = pci->dev;
> u32 tmp;
> @@ -558,15 +576,11 @@ static int imx6_pcie_establish_link(struct imx6_pcie *imx6_pcie)
> tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
> tmp |= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1;
> dw_pcie_writel_dbi(pci, PCIE_RC_LCR, tmp);
>
> /* Start LTSSM. */
> - if (imx6_pcie->variant == IMX7D)
> - reset_control_deassert(imx6_pcie->apps_reset);
> - else
> - regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> - IMX6Q_GPR12_PCIE_CTL_2, 1 << 10);
> + imx6_pcie_ltssm_enable(dev);
>
> ret = imx6_pcie_wait_for_link(imx6_pcie);
> if (ret)
> goto err_reset_phy;
>
> @@ -680,10 +694,82 @@ static int imx6_add_pcie_port(struct imx6_pcie *imx6_pcie,
>
> static const struct dw_pcie_ops dw_pcie_ops = {
> .link_up = imx6_pcie_link_up,
> };
>
> +#ifdef CONFIG_PM_SLEEP
> +static void imx6_pcie_ltssm_disable(struct device *dev)
> +{
> + struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> +
> + switch (imx6_pcie->variant) {
> + case IMX6SX:
> + case IMX6QP:
> + regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> + IMX6Q_GPR12_PCIE_CTL_2, 0);
> + break;
> + case IMX7D:
> + reset_control_assert(imx6_pcie->apps_reset);
> + break;
> + default:
> + dev_err(dev, "ltssm_disable not supported\n");
> + }
> +}
> +
> +static void imx6_pcie_clk_disable(struct imx6_pcie *imx6_pcie)
> +{
> + clk_disable_unprepare(imx6_pcie->pcie);
> + clk_disable_unprepare(imx6_pcie->pcie_phy);
> + clk_disable_unprepare(imx6_pcie->pcie_bus);
> +
> + if (imx6_pcie->variant == IMX7D) {
> + regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> + IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
> + IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> + }
> +}
> +
> +static int imx6_pcie_suspend_noirq(struct device *dev)
> +{
> + struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> +
> + if (imx6_pcie->variant != IMX7D)
> + return 0;
> +
> + imx6_pcie_clk_disable(imx6_pcie);
> + imx6_pcie_ltssm_disable(dev);
> +
> + return 0;
> +}
> +
> +static int imx6_pcie_resume_noirq(struct device *dev)
> +{
> + int ret;
> + struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> + struct pcie_port *pp = &imx6_pcie->pci->pp;
> +
> + if (imx6_pcie->variant != IMX7D)
> + return 0;
> +
> + imx6_pcie_assert_core_reset(imx6_pcie);
> + imx6_pcie_init_phy(imx6_pcie);
> + imx6_pcie_deassert_core_reset(imx6_pcie);
> + dw_pcie_setup_rc(pp);
> +
> + ret = imx6_pcie_establish_link(imx6_pcie);
> + if (ret < 0)
> + dev_info(dev, "pcie link is down after resume.\n");
> +
> + return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops imx6_pcie_pm_ops = {
> + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx6_pcie_suspend_noirq,
> + imx6_pcie_resume_noirq)
> +};
> +
> static int imx6_pcie_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> struct dw_pcie *pci;
> struct imx6_pcie *imx6_pcie;
> @@ -846,10 +932,11 @@ static const struct of_device_id imx6_pcie_of_match[] = {
> static struct platform_driver imx6_pcie_driver = {
> .driver = {
> .name = "imx6q-pcie",
> .of_match_table = imx6_pcie_of_match,
> .suppress_bind_attrs = true,
> + .pm = &imx6_pcie_pm_ops,
> },
> .probe = imx6_pcie_probe,
> .shutdown = imx6_pcie_shutdown,
> };
>
> --
> 2.17.1
>
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