Am Montag, den 01.10.2018, 22:53 +0300 schrieb Leonard Crestez:
> When the root complex suspends it must send a PME_Turn_Off TLP.
> Implement this by asserting the "turnoff" reset.
>
> On imx7d this is functionality is part of the SRC and exposed through
> the linux reset-controller subsystem. On imx6 equivalent bits are in the
> IOMUXC GPR area which the imx6-pcie driver accesses directly.
>
> This is only for imx7d right now but it's deliberately implemented as an
> optional reset, ignoring the chip variant:
> * Older dtbs won't have this reset so it will be ignored.
> * Future chips might also expose this as a reset controller.
>
> For example imx8m (not yet supported) has the exact same
> PCIE_CTRL_APPS_TURNOFF bit in the same location.
>
> > Signed-off-by: Leonard Crestez <leonard.cres...@nxp.com>
> ---
> drivers/pci/controller/dwc/pci-imx6.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> b/drivers/pci/controller/dwc/pci-imx6.c
> index 6ba16fd1373c..13cb1a200442 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -50,10 +50,11 @@ struct imx6_pcie {
> > > struct clk *pcie_inbound_axi;
> > > struct clk *pcie;
> > > struct regmap *iomuxc_gpr;
> > > struct reset_control *pciephy_reset;
> > > struct reset_control *apps_reset;
> > > + struct reset_control *turnoff_reset;
> > enum imx6_pcie_variants variant;
> > > u32 tx_deemph_gen1;
> > > u32 tx_deemph_gen2_3p5db;
> > > u32 tx_deemph_gen2_6db;
> > > u32 tx_swing_full;
> @@ -812,10 +813,16 @@ static void imx6_pcie_ltssm_disable(struct device *dev)
> > default:
> > dev_err(dev, "ltssm_disable not supported\n");
> > }
> }
>
> +static void imx6_pcie_pm_turnoff(struct imx6_pcie *imx6_pcie)
> +{
> > + reset_control_assert(imx6_pcie->turnoff_reset);
> + reset_control_deassert(imx6_pcie->turnoff_reset);
I'm a bit surprised to see no timing requirements here. I would have
expected that there is a minimum time from asserting the reset, so the
turnoff message gets transmitted to the EP before the clocks are
stopped.
Regards,
Lucas
> +}
> +
> 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);
> @@ -832,10 +839,11 @@ 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_pm_turnoff(imx6_pcie);
> > imx6_pcie_clk_disable(imx6_pcie);
> > imx6_pcie_ltssm_disable(dev);
>
> > return 0;
> }
> @@ -959,10 +967,17 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> > break;
> > default:
> > break;
> > }
>
> > + /* Grab turnoff reset */
> > + imx6_pcie->turnoff_reset =
> > devm_reset_control_get_optional_exclusive(dev, "turnoff");
> > + if (IS_ERR(imx6_pcie->turnoff_reset)) {
> > + dev_err(dev, "Failed to get TURNOFF reset control\n");
> > + return PTR_ERR(imx6_pcie->turnoff_reset);
> > + }
> +
> > /* Grab GPR config register range */
> > imx6_pcie->iomuxc_gpr =
> > syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
> > if (IS_ERR(imx6_pcie->iomuxc_gpr)) {
> > dev_err(dev, "unable to find iomuxc registers\n");
