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Date: Wed, 23 Aug 2023 10:15:20 -0400
From: Frank Li <Frank.li@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>, bhelgaas@...gle.com,
devicetree@...r.kernel.org, gustavo.pimentel@...opsys.com,
helgaas@...nel.org, imx@...ts.linux.dev, kw@...ux.com,
leoyang.li@....com, linux-arm-kernel@...ts.infradead.org,
linux-imx@....com, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, lorenzo.pieralisi@....com,
mani@...nel.org, minghuan.lian@....com, mingkai.hu@....com,
robh+dt@...nel.org, roy.zang@....com, shawnguo@...nel.org,
zhiqiang.hou@....com
Subject: Re: [PATCH v12 3/3] PCI: layerscape: Add power management support
for ls1028a
On Wed, Aug 23, 2023 at 01:23:05PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Aug 22, 2023 at 10:30:08AM -0400, Frank Li wrote:
> > On Tue, Aug 22, 2023 at 11:02:11AM +0200, Lorenzo Pieralisi wrote:
> > > On Mon, Aug 21, 2023 at 02:48:15PM -0400, Frank Li wrote:
> > > > From: Hou Zhiqiang <Zhiqiang.Hou@....com>
> > > >
> > > > Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform. Call
> > > > common dwc dw_pcie_suspend(resume)_noirq() function when system enter/exit
> > > > suspend state.
> > > >
> > > > Acked-by: Manivannan Sadhasivam <mani@...nel.org>
> > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
> > > > Signed-off-by: Frank Li <Frank.Li@....com>
> > > > ---
> > > > drivers/pci/controller/dwc/pci-layerscape.c | 135 ++++++++++++++++++--
> > > > 1 file changed, 126 insertions(+), 9 deletions(-)
> > > >
> > > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> > > > index ed5fb492fe08..97b8d3329df7 100644
> > > > --- a/drivers/pci/controller/dwc/pci-layerscape.c
> > > > +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> > > > @@ -8,9 +8,11 @@
> > > > * Author: Minghuan Lian <Minghuan.Lian@...escale.com>
> > > > */
> > > >
> > > > +#include <linux/delay.h>
> > > > #include <linux/kernel.h>
> > > > #include <linux/interrupt.h>
> > > > #include <linux/init.h>
> > > > +#include <linux/iopoll.h>
> > > > #include <linux/of_pci.h>
> > > > #include <linux/of_platform.h>
> > > > #include <linux/of_address.h>
> > > > @@ -20,6 +22,7 @@
> > > > #include <linux/mfd/syscon.h>
> > > > #include <linux/regmap.h>
> > > >
> > > > +#include "../../pci.h"
> > > > #include "pcie-designware.h"
> > > >
> > > > /* PEX Internal Configuration Registers */
> > > > @@ -27,12 +30,26 @@
> > > > #define PCIE_ABSERR 0x8d0 /* Bridge Slave Error Response Register */
> > > > #define PCIE_ABSERR_SETTING 0x9401 /* Forward error of non-posted request */
> > > >
> > > > +/* PF Message Command Register */
> > > > +#define LS_PCIE_PF_MCR 0x2c
> > > > +#define PF_MCR_PTOMR BIT(0)
> > > > +#define PF_MCR_EXL2S BIT(1)
> > > > +
> > > > #define PCIE_IATU_NUM 6
> > > >
> > > > +struct ls_pcie_drvdata {
> > > > + const u32 pf_off;
> > > > + bool pm_support;
> > > > +};
> > > > +
> > > > struct ls_pcie {
> > > > struct dw_pcie *pci;
> > > > + const struct ls_pcie_drvdata *drvdata;
> > > > + void __iomem *pf_base;
> > > > + bool big_endian;
> > > > };
> > > >
> > > > +#define ls_pcie_pf_readl_addr(addr) ls_pcie_pf_readl(pcie, addr)
> > > > #define to_ls_pcie(x) dev_get_drvdata((x)->dev)
> > > >
> > > > static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
> > > > @@ -73,6 +90,64 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
> > > > iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
> > > > }
> > > >
> > > > +static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
> > > > +{
> > > > + if (pcie->big_endian)
> > > > + return ioread32be(pcie->pf_base + off);
> > > > +
> > > > + return ioread32(pcie->pf_base + off);
> > > > +}
> > > > +
> > > > +static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
> > > > +{
> > > > + if (pcie->big_endian)
> > > > + iowrite32be(val, pcie->pf_base + off);
> > > > + else
> > > > + iowrite32(val, pcie->pf_base + off);
> > > > +}
> > > > +
> > > > +static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
> > > > +{
> > > > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > + struct ls_pcie *pcie = to_ls_pcie(pci);
> > > > + u32 val;
> > > > + int ret;
> > > > +
> > > > + val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > > + val |= PF_MCR_PTOMR;
> > > > + ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > > +
> > > > + ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > > + val, !(val & PF_MCR_PTOMR),
> > > > + PCIE_PME_TO_L2_TIMEOUT_US/10,
> > > > + PCIE_PME_TO_L2_TIMEOUT_US);
> > > > + if (ret)
> > > > + dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
> > > > +}
> > > > +
> > > > +static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
> > > > +{
> > > > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > + struct ls_pcie *pcie = to_ls_pcie(pci);
> > > > + u32 val;
> > > > + int ret;
> > > > +
> > > > + /*
> > > > + * Set PF_MCR_EXL2S bit in LS_PCIE_PF_MCR register for the link
> > > > + * to exit L2 state.
> > > > + */
> > > > + val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
> > > > + val |= PF_MCR_EXL2S;
> > > > + ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
> > > > +
> > > > + ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
> > > > + val, !(val & PF_MCR_EXL2S),
> > > > + 1000,
> > > > + 10000);
> > >
> > > I can add a comment myself - please explain how this delay was chosen,
> > > any piece of information could be useful for a future developer, let
> > > me know and I will add it.
> >
> > (This value is coming from exited downstream code. It is really hard to
> > find original owner and designer to find the reason).
> >
> > How about just add below comments?
> >
> > "No specific specification defines this timeout value. The timemout of 10ms
> > was chosen by the engineer as a sufficient amount of time to allow the
> > hardware to complete its actions."
> >
>
> How about, "L1 exit timeout of 10ms is not defined in the spec, but rather
> chosen based on the practical observations."
Great!
Frank
>
> - Mani
>
> > >
> > > > + if (ret)
> > > > + dev_err(pcie->pci->dev, "L2 exit timeout\n");
> > > > +}
> > > > +
> > > > static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> > > > {
> > > > struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > > @@ -91,18 +166,27 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> > > >
> > > > static const struct dw_pcie_host_ops ls_pcie_host_ops = {
> > > > .host_init = ls_pcie_host_init,
> > > > + .pme_turn_off = ls_pcie_send_turnoff_msg,
> > > > +};
> > > > +
> > > > +static const struct ls_pcie_drvdata ls1021a_drvdata = {
> > >
> > > I suggest adding .pm_support = false explicitly here, I can
> > > do it myself.
> > >
> > > Thanks,
> > > Lorenzo
> >
> > Thanks!
> >
> > >
> > > > +};
> > > > +
> > > > +static const struct ls_pcie_drvdata layerscape_drvdata = {
> > > > + .pf_off = 0xc0000,
> > > > + .pm_support = true,
> > > > };
> > > >
> > > > static const struct of_device_id ls_pcie_of_match[] = {
> > > > - { .compatible = "fsl,ls1012a-pcie", },
> > > > - { .compatible = "fsl,ls1021a-pcie", },
> > > > - { .compatible = "fsl,ls1028a-pcie", },
> > > > - { .compatible = "fsl,ls1043a-pcie", },
> > > > - { .compatible = "fsl,ls1046a-pcie", },
> > > > - { .compatible = "fsl,ls2080a-pcie", },
> > > > - { .compatible = "fsl,ls2085a-pcie", },
> > > > - { .compatible = "fsl,ls2088a-pcie", },
> > > > - { .compatible = "fsl,ls1088a-pcie", },
> > > > + { .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
> > > > + { .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
> > > > + { .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
> > > > + { .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
> > > > + { .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
> > > > + { .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
> > > > + { .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
> > > > + { .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
> > > > + { .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
> > > > { },
> > > > };
> > > >
> > > > @@ -121,6 +205,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
> > > > if (!pci)
> > > > return -ENOMEM;
> > > >
> > > > + pcie->drvdata = of_device_get_match_data(dev);
> > > > +
> > > > pci->dev = dev;
> > > > pci->pp.ops = &ls_pcie_host_ops;
> > > >
> > > > @@ -131,6 +217,10 @@ static int ls_pcie_probe(struct platform_device *pdev)
> > > > if (IS_ERR(pci->dbi_base))
> > > > return PTR_ERR(pci->dbi_base);
> > > >
> > > > + pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
> > > > +
> > > > + pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
> > > > +
> > > > if (!ls_pcie_is_bridge(pcie))
> > > > return -ENODEV;
> > > >
> > > > @@ -139,12 +229,39 @@ static int ls_pcie_probe(struct platform_device *pdev)
> > > > return dw_pcie_host_init(&pci->pp);
> > > > }
> > > >
> > > > +static int ls_pcie_suspend_noirq(struct device *dev)
> > > > +{
> > > > + struct ls_pcie *pcie = dev_get_drvdata(dev);
> > > > +
> > > > + if (!pcie->drvdata->pm_support)
> > > > + return 0;
> > > > +
> > > > + return dw_pcie_suspend_noirq(pcie->pci);
> > > > +}
> > > > +
> > > > +static int ls_pcie_resume_noirq(struct device *dev)
> > > > +{
> > > > + struct ls_pcie *pcie = dev_get_drvdata(dev);
> > > > +
> > > > + if (!pcie->drvdata->pm_support)
> > > > + return 0;
> > > > +
> > > > + ls_pcie_exit_from_l2(&pcie->pci->pp);
> > > > +
> > > > + return dw_pcie_resume_noirq(pcie->pci);
> > > > +}
> > > > +
> > > > +static const struct dev_pm_ops ls_pcie_pm_ops = {
> > > > + NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq, ls_pcie_resume_noirq)
> > > > +};
> > > > +
> > > > static struct platform_driver ls_pcie_driver = {
> > > > .probe = ls_pcie_probe,
> > > > .driver = {
> > > > .name = "layerscape-pcie",
> > > > .of_match_table = ls_pcie_of_match,
> > > > .suppress_bind_attrs = true,
> > > > + .pm = &ls_pcie_pm_ops,
> > > > },
> > > > };
> > > > builtin_platform_driver(ls_pcie_driver);
> > > > --
> > > > 2.34.1
> > > >
>
> --
> மணிவண்ணன் சதாசிவம்
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