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

Hongxing Zhu
2024-10-24T07:43:50Z

> -----Original Message-----
> From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Sent: 2024年10月23日 1:18
> To: Hongxing Zhu <hongxing.zhu@nxp.com>
> Cc: kw@linux.com; bhelgaas@google.com; lpieralisi@kernel.org; Frank Li
> <frank.li@nxp.com>; l.stach@pengutronix.de; robh+dt@kernel.org;
> conor+dt@kernel.org; shawnguo@kernel.org;
> krzysztof.kozlowski+dt@linaro.org; festevam@gmail.com;
> s.hauer@pengutronix.de; linux-pci@vger.kernel.org;
> linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> devicetree@vger.kernel.org; kernel@pengutronix.de; imx@lists.linux.dev
> 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@nxp.com>
> >
> > 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@nxp.com>
> > Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> > ---
> > 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
>
> --
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