linux-kernel - Re: [PATCH v2] PCI: imx: Add imx6sx suspend/resume support

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Date:   Thu, 22 Nov 2018 12:50:02 +0100
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Leonard Crestez <leonard.crestez@....com>
Cc:     Philipp Zabel <p.zabel@...gutronix.de>,
        Richard Zhu <hongxing.zhu@....com>,
        Andrey Smirnov <andrew.smirnov@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        "A.s. Dong" <aisheng.dong@....com>,
        dl-linux-imx <linux-imx@....com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH v2] PCI: imx: Add imx6sx suspend/resume support

Am Donnerstag, den 22.11.2018, 11:38 +0000 schrieb Lorenzo Pieralisi:
> On Wed, Nov 07, 2018 at 01:57:03PM +0000, Leonard Crestez wrote:
> > Enable PCI suspend/resume support on imx6sx socs. This is similar to
> > imx7d with a few differences:
> > 
> > * The PM_Turn_Off bit is exposed through an IOMUX GPR, like all other
> > pcie control bits on 6sx.
> > * The pcie_inbound_axi clk needs to be turned off in suspend. On resume
> > it is restored via resume -> deassert_core_reset -> enable_ref_clk.
> > 
> > Most of the resume logic is shared with the initial reset after probe.
> > 
> > > > Signed-off-by: Leonard Crestez <leonard.crestez@....com>
> > 
> > ---
> > Changes since v1:
> > * Use a switch statement in imx6_pcie_pm_turnoff. The DT-based turnoff
> > path is still an if statement.
> > * Did not split imx6_pcie_clk_disable or call it from other paths, this
> > would bring complications and is somewhat unrelated.
> > * See v1 comments: https://lore.kernel.org/patchwork/patch/996806/
> > 
> >  drivers/pci/controller/dwc/pci-imx6.c       | 44 ++++++++++++++++++---
> >  include/linux/mfd/syscon/imx6q-iomuxc-gpr.h |  1 +
> >  2 files changed, 40 insertions(+), 5 deletions(-)
> 
> I request Richard/Lucas ACK in order to merge this patch.

I'm fine with this patch.

Acked-by: Lucas Stach <l.stach@...gutronix.de>


> Thanks,
> Lorenzo
> 
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index 2cbef2d7c207..54625569d0bc 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -771,41 +771,75 @@ static void imx6_pcie_ltssm_disable(struct device *dev)
> > > >  	}
> >  }
> >  
> >  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);
> > > > +	struct device *dev = imx6_pcie->pci->dev;
> > +
> > > > +	/* Some variants have a turnoff reset in DT */
> > > > +	if (imx6_pcie->turnoff_reset) {
> > > > +		reset_control_assert(imx6_pcie->turnoff_reset);
> > > > +		reset_control_deassert(imx6_pcie->turnoff_reset);
> > > > +		goto pm_turnoff_sleep;
> > > > +	}
> > +
> > > > +	/* Others poke directly at IOMUXC registers */
> > > > +	switch (imx6_pcie->variant) {
> > > > +	case IMX6SX:
> > > > +		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > > > +				IMX6SX_GPR12_PCIE_PM_TURN_OFF,
> > > > +				IMX6SX_GPR12_PCIE_PM_TURN_OFF);
> > > > +		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > > > +				IMX6SX_GPR12_PCIE_PM_TURN_OFF, 0);
> > > > +		break;
> > > > +	default:
> > > > +		dev_err(dev, "PME_Turn_Off not implemented\n");
> > > > +		return;
> > > > +	}
> >  
> > > >  	/*
> > > >  	 * Components with an upstream port must respond to
> > > >  	 * PME_Turn_Off with PME_TO_Ack but we can't check.
> > > >  	 *
> > > >  	 * The standard recommends a 1-10ms timeout after which to
> > > >  	 * proceed anyway as if acks were received.
> > > >  	 */
> > +pm_turnoff_sleep:
> > > >  	usleep_range(1000, 10000);
> >  }
> >  
> >  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) {
> > > > +	switch (imx6_pcie->variant) {
> > > > +	case IMX6SX:
> > > > +		clk_disable_unprepare(imx6_pcie->pcie_inbound_axi);
> > > > +		break;
> > > > +	case IMX7D:
> > > >  		regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > > >  				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
> > > >  				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> > > > +		break;
> > > > +	default:
> > > > +		break;
> > > >  	}
> >  }
> >  
> > +static inline bool imx6_pcie_supports_suspend(struct imx6_pcie *imx6_pcie)
> > +{
> > > > +	return (imx6_pcie->variant == IMX7D ||
> > > > +		imx6_pcie->variant == IMX6SX);
> > +}
> > +
> >  static int imx6_pcie_suspend_noirq(struct device *dev)
> >  {
> > > >  	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> >  
> > > > -	if (imx6_pcie->variant != IMX7D)
> > > > +	if (!imx6_pcie_supports_suspend(imx6_pcie))
> > > >  		return 0;
> >  
> > > >  	imx6_pcie_pm_turnoff(imx6_pcie);
> > > >  	imx6_pcie_clk_disable(imx6_pcie);
> > > >  	imx6_pcie_ltssm_disable(dev);
> > @@ -817,11 +851,11 @@ 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)
> > > > +	if (!imx6_pcie_supports_suspend(imx6_pcie))
> > > >  		return 0;
> >  
> > > >  	imx6_pcie_assert_core_reset(imx6_pcie);
> > > >  	imx6_pcie_init_phy(imx6_pcie);
> > > >  	imx6_pcie_deassert_core_reset(imx6_pcie);
> > diff --git a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > index 6c1ad160ed87..c1b25f5e386d 100644
> > --- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > +++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > @@ -438,10 +438,11 @@
> > > >  #define IMX6SX_GPR5_DISP_MUX_DCIC1_LCDIF1		(0x0 << 1)
> > > >  #define IMX6SX_GPR5_DISP_MUX_DCIC1_LVDS			(0x1 << 1)
> > > >  #define IMX6SX_GPR5_DISP_MUX_DCIC1_MASK			(0x1 << 1)
> >  
> > > >  #define IMX6SX_GPR12_PCIE_TEST_POWERDOWN		BIT(30)
> > > > +#define IMX6SX_GPR12_PCIE_PM_TURN_OFF			BIT(16)
> > > >  #define IMX6SX_GPR12_PCIE_RX_EQ_MASK			(0x7 << 0)
> > > >  #define IMX6SX_GPR12_PCIE_RX_EQ_2			(0x2 << 0)
> >  
> >  /* For imx6ul iomux gpr register field define */
> > > >  #define IMX6UL_GPR1_ENET1_CLK_DIR		(0x1 << 17)
> > -- 
> > 2.17.1
> >