RE: [PATCH v4 7/9] PCI: imx6: Use dwc common suspend resume method

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> -----Original Message-----
> From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Sent: 2024年10月23日 1:18
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: kw@xxxxxxxxx; bhelgaas@xxxxxxxxxx; lpieralisi@xxxxxxxxxx; Frank Li
> <frank.li@xxxxxxx>; l.stach@xxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> conor+dt@xxxxxxxxxx; shawnguo@xxxxxxxxxx;
> krzysztof.kozlowski+dt@xxxxxxxxxx; festevam@xxxxxxxxx;
> s.hauer@xxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v4 7/9] PCI: imx6: Use dwc common suspend resume
> method
> 
> On Tue, Oct 15, 2024 at 04:33:31PM +0800, Richard Zhu wrote:
> > From: Frank Li <Frank.Li@xxxxxxx>
> >
> > Call common dwc suspend/resume function. Use dwc common iATU
> method to
> > send out PME_TURN_OFF message. Old platform such as iMX6SX and
> iMX6QP,
> > iATU
> > CTRL2 bit 22 (PCIE_ATU_INHIBIT_PAYLOAD) are reserved. So can't send
> > out MSG without data by dummy MMIO write. Without
> > PCIE_ATU_INHIBIT_PAYLOAD, MSGD will be sent out instead of MSG. So
> > keep old method to send PME_TURN_OFF MSG.
> >
> 
> This PME_Turn_Off implementation is the only difference between the DWC
> common ops and the custom one here? I don't think so. Please describe all
> the differences.
> 
Hi Manivannan:
Thanks for your comments.
On i.MX6SX and i.MX6QP platforms, the PME_TURN_OFF would be issued by the
 hooked callback pp.ops->pme_turn_off(). They are same to the previous
 operations.

In the other words, these two platforms don't use the dwc generic
 PME_TURN_OFF implementation.

Do you means to describe all the differences between dwc common suspend/resume
and custom suspend/resume in commit message?

In dwc suspend, the l1ss and link stats are checked before suspend entry.
And after PME_TURN_OFF is issued, the L2 stat is polling.

These two differences are not contained in the custom PM operations.

> > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 97
> > ++++++++++-----------------
> >  1 file changed, 36 insertions(+), 61 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 161daad34a94..baa853d84b4d 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -33,6 +33,7 @@
> >  #include <linux/pm_domain.h>
> >  #include <linux/pm_runtime.h>
> >
> > +#include "../../pci.h"
> >  #include "pcie-designware.h"
> >
> >  #define IMX8MQ_GPR_PCIE_REF_USE_PAD		BIT(9)
> > @@ -82,6 +83,7 @@ enum imx_pcie_variants {
> >  #define IMX_PCIE_FLAG_HAS_SERDES		BIT(6)
> >  #define IMX_PCIE_FLAG_SUPPORT_64BIT		BIT(7)
> >  #define IMX_PCIE_FLAG_CPU_ADDR_FIXUP		BIT(8)
> > +#define IMX_PCIE_FLAG_CUSTOM_PME_TURNOFF	BIT(9)
> >
> >  #define imx_check_flag(pci, val)	(pci->drvdata->flags & val)
> >
> > @@ -106,19 +108,18 @@ struct imx_pcie_drvdata {
> >  	int (*init_phy)(struct imx_pcie *pcie);
> >  	int (*enable_ref_clk)(struct imx_pcie *pcie, bool enable);
> >  	int (*core_reset)(struct imx_pcie *pcie, bool assert);
> > +	const struct dw_pcie_host_ops *ops;
> >  };
> >
> >  struct imx_pcie {
> >  	struct dw_pcie		*pci;
> >  	struct gpio_desc	*reset_gpiod;
> > -	bool			link_is_up;
> >  	struct clk_bulk_data	clks[IMX_PCIE_MAX_CLKS];
> >  	struct regmap		*iomuxc_gpr;
> >  	u16			msi_ctrl;
> >  	u32			controller_id;
> >  	struct reset_control	*pciephy_reset;
> >  	struct reset_control	*apps_reset;
> > -	struct reset_control	*turnoff_reset;
> >  	u32			tx_deemph_gen1;
> >  	u32			tx_deemph_gen2_3p5db;
> >  	u32			tx_deemph_gen2_6db;
> > @@ -898,13 +899,11 @@ static int imx_pcie_start_link(struct dw_pcie
> *pci)
> >  		dev_info(dev, "Link: Only Gen1 is enabled\n");
> >  	}
> >
> > -	imx_pcie->link_is_up = true;
> >  	tmp = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
> >  	dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS);
> >  	return 0;
> >
> >  err_reset_phy:
> > -	imx_pcie->link_is_up = false;
> >  	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)); @@ -1023,9
> +1022,33 @@
> > static u64 imx_pcie_cpu_addr_fixup(struct dw_pcie *pcie, u64 cpu_addr)
> >  	return cpu_addr - entry->offset;
> >  }
> >
> > +/*
> > + * Old dwc iATU ctrl2 bit 22 (PCIE_ATU_INHIBIT_PAYLOAD) are reserved.
> > +So can't
> > + * send out MSG without data by dummy MMIO write. Without
> > + * PCIE_ATU_INHIBIT_PAYLOAD, MSGD will be sent out. So have to keep
> > +old method
> > + * to send PME_TURN_OFF MSG.
> 
> Please reword the comments:
> 
> "In Old DWC implementations, PCIE_ATU_INHIBIT_PAYLOAD bit in iATU Ctrl2
> register is reserved. So the generic DWC implementation of sending the
> PME_Turn_Off message using a dummy MMIO write cannot be used."
> 
> > + */
> > +static void imx_pcie_pm_turn_off(struct dw_pcie_rp *pp)
> 
> s/pm/pme
> 
> > +{
> > +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > +	struct imx_pcie *imx_pcie = to_imx_pcie(pci);
> > +
> > +	regmap_set_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> IMX6SX_GPR12_PCIE_PM_TURN_OFF);
> > +	regmap_clear_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > +IMX6SX_GPR12_PCIE_PM_TURN_OFF);
> > +
> > +	usleep_range(PCIE_PME_TO_L2_TIMEOUT_US/10,
> > +PCIE_PME_TO_L2_TIMEOUT_US); }
> > +
> > +
> >  static const struct dw_pcie_host_ops imx_pcie_host_ops = {
> >  	.init = imx_pcie_host_init,
> >  	.deinit = imx_pcie_host_exit,
> > +	.pme_turn_off = imx_pcie_pm_turn_off, };
> > +
> > +static const struct dw_pcie_host_ops imx_pcie_host_dw_pme_ops = {
> > +	.init = imx_pcie_host_init,
> > +	.deinit = imx_pcie_host_exit,
> >  };
> >
> >  static const struct dw_pcie_ops dw_pcie_ops = { @@ -1146,43 +1169,6
> > @@ static int imx_add_pcie_ep(struct imx_pcie *imx_pcie,
> >  	return 0;
> >  }
> >
> > -static void imx_pcie_pm_turnoff(struct imx_pcie *imx_pcie) -{
> > -	struct device *dev = imx_pcie->pci->dev;
> > -
> > -	/* Some variants have a turnoff reset in DT */
> > -	if (imx_pcie->turnoff_reset) {
> > -		reset_control_assert(imx_pcie->turnoff_reset);
> > -		reset_control_deassert(imx_pcie->turnoff_reset);
> > -		goto pm_turnoff_sleep;
> > -	}
> 
> What about this part of the code? Don't you need it now?
> 
> > -
> > -	/* Others poke directly at IOMUXC registers */
> > -	switch (imx_pcie->drvdata->variant) {
> > -	case IMX6SX:
> > -	case IMX6QP:
> > -		regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > -				IMX6SX_GPR12_PCIE_PM_TURN_OFF,
> > -				IMX6SX_GPR12_PCIE_PM_TURN_OFF);
> > -		regmap_update_bits(imx_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 imx_pcie_msi_save_restore(struct imx_pcie *imx_pcie, bool
> > save)  {
> >  	u8 offset;
> > @@ -1206,36 +1192,26 @@ static void imx_pcie_msi_save_restore(struct
> > imx_pcie *imx_pcie, bool save)  static int
> > imx_pcie_suspend_noirq(struct device *dev)  {
> >  	struct imx_pcie *imx_pcie = dev_get_drvdata(dev);
> > -	struct dw_pcie_rp *pp = &imx_pcie->pci->pp;
> >
> >  	if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND))
> >  		return 0;
> >
> >  	imx_pcie_msi_save_restore(imx_pcie, true);
> > -	imx_pcie_pm_turnoff(imx_pcie);
> > -	imx_pcie_stop_link(imx_pcie->pci);
> > -	imx_pcie_host_exit(pp);
> > -
> > -	return 0;
> > +	return dw_pcie_suspend_noirq(imx_pcie->pci);
> >  }
> >
> >  static int imx_pcie_resume_noirq(struct device *dev)  {
> >  	int ret;
> >  	struct imx_pcie *imx_pcie = dev_get_drvdata(dev);
> > -	struct dw_pcie_rp *pp = &imx_pcie->pci->pp;
> >
> >  	if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND))
> >  		return 0;
> >
> > -	ret = imx_pcie_host_init(pp);
> > +	ret = dw_pcie_resume_noirq(imx_pcie->pci);
> >  	if (ret)
> >  		return ret;
> >  	imx_pcie_msi_save_restore(imx_pcie, false);
> > -	dw_pcie_setup_rc(pp);
> > -
> > -	if (imx_pcie->link_is_up)
> > -		imx_pcie_start_link(imx_pcie->pci);
> 
> So this is also not needed? Why? Please explain in the commit message.
These codes would be invoked from dw_pcie_resume_noirq() too.

Frank had pointed the invoke procedure.
Would add them into commit message later.

Best Regards
Richard
> 
> - Mani
> 
> --
> மணிவண்ணன் சதாசிவம்




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