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Message-ID: <20231017081731.GD5274@thinkpad>
Date: Tue, 17 Oct 2023 13:47:31 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Frank Li <Frank.li@....com>
Cc: Minghuan Lian <minghuan.Lian@....com>,
Mingkai Hu <mingkai.hu@....com>, Roy Zang <roy.zang@....com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Rob Herring <robh@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"open list:PCI DRIVER FOR FREESCALE LAYERSCAPE"
<linuxppc-dev@...ts.ozlabs.org>,
"open list:PCI DRIVER FOR FREESCALE LAYERSCAPE"
<linux-pci@...r.kernel.org>,
"moderated list:PCI DRIVER FOR FREESCALE LAYERSCAPE"
<linux-arm-kernel@...ts.infradead.org>,
open list <linux-kernel@...r.kernel.org>, imx@...ts.linux.dev
Subject: Re: [PATCH 2/3] PCI: layerscape: add suspend/resume for ls1021a
On Mon, Oct 16, 2023 at 04:18:36PM -0400, Frank Li wrote:
> On Mon, Oct 16, 2023 at 10:28:24PM +0530, Manivannan Sadhasivam wrote:
> > On Fri, Sep 15, 2023 at 02:43:05PM -0400, Frank Li wrote:
> > > ls1021a add suspend/resume support.
> > >
> >
> > Please add what the driver is doing during suspend/resume.
> >
> > > Signed-off-by: Frank Li <Frank.Li@....com>
> > > ---
> > > drivers/pci/controller/dwc/pci-layerscape.c | 88 ++++++++++++++++++++-
> > > 1 file changed, 87 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
> > > index 20c48c06e2248..bc5a8ff1a26ce 100644
> > > --- a/drivers/pci/controller/dwc/pci-layerscape.c
> > > +++ b/drivers/pci/controller/dwc/pci-layerscape.c
> > > @@ -35,6 +35,12 @@
> > > #define PF_MCR_PTOMR BIT(0)
> > > #define PF_MCR_EXL2S BIT(1)
> > >
> > > +/* LS1021A PEXn PM Write Control Register */
> > > +#define SCFG_PEXPMWRCR(idx) (0x5c + (idx) * 0x64)
> > > +#define PMXMTTURNOFF BIT(31)
> > > +#define SCFG_PEXSFTRSTCR 0x190
> > > +#define PEXSR(idx) BIT(idx)
> > > +
> > > #define PCIE_IATU_NUM 6
> > >
> > > struct ls_pcie_drvdata {
> > > @@ -48,6 +54,8 @@ struct ls_pcie {
> > > struct dw_pcie *pci;
> > > const struct ls_pcie_drvdata *drvdata;
> > > void __iomem *pf_base;
> > > + struct regmap *scfg;
> > > + int index;
> > > bool big_endian;
> > > };
> > >
> > > @@ -170,13 +178,91 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
> > > return 0;
> > > }
> > >
> > > +static void ls1021a_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;
> > > +
> > > + if (!pcie->scfg) {
> >
> > Can this ever happen?
> >
> > > + dev_dbg(pcie->pci->dev, "SYSCFG is NULL\n");
> > > + return;
> > > + }
> > > +
> > > + /* Send Turn_off message */
> >
> > "Send PME_Turn_Off message"
> >
> > > + regmap_read(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), &val);
> > > + val |= PMXMTTURNOFF;
> > > + regmap_write(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), val);
> > > +
> > > + /* There are not register to check ACK, so wait PCIE_PME_TO_L2_TIMEOUT_US */
> >
> > "There is no specific register to check for PME_To_Ack from endpoint. So on the
> > safe side, wait for PCIE_PME_TO_L2_TIMEOUT_US."
> >
> > > + mdelay(PCIE_PME_TO_L2_TIMEOUT_US/1000);
> > > +
> > > + /* Clear Turn_off message */
> >
> > "PME_Turn_off". But I'm not sure if this is really required. Are you doing it
> > because the layerspace hw implements the PME_Turn_Off bit as "level triggered"?
>
> I am not sure how hardware implement this. But reference manual said:
>
> PMXMTTURNOFF:
> Generate PM turnoff message for power management of PCI Express controllers.
> This bit should be cleared by software.
> 0 Clear PM turnoff (default)
> 1 Trigger PM turnoff
>
Hmm, okay. Atleast add the below comment to make it understandable in the
future:
"Layerscape hardware reference manual recommends clearing the PMXMTTURNOFF bit
to complete the PME_Turn_Off handshake."
- Mani
> Frank
>
> >
> > > + regmap_read(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), &val);
> > > + val &= ~PMXMTTURNOFF;
> > > + regmap_write(pcie->scfg, SCFG_PEXPMWRCR(pcie->index), val);
> > > +}
> > > +
> > > +static void ls1021a_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;
> > > +
> >
> > A comment here would be good.
> >
> > > + regmap_read(pcie->scfg, SCFG_PEXSFTRSTCR, &val);
> > > + val |= PEXSR(pcie->index);
> > > + regmap_write(pcie->scfg, SCFG_PEXSFTRSTCR, val);
> > > +
> > > + regmap_read(pcie->scfg, SCFG_PEXSFTRSTCR, &val);
> > > + val &= ~PEXSR(pcie->index);
> > > + regmap_write(pcie->scfg, SCFG_PEXSFTRSTCR, val);
> > > +}
> > > +
> > > +static int ls1021a_pcie_host_init(struct dw_pcie_rp *pp)
> > > +{
> > > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > + struct ls_pcie *pcie = to_ls_pcie(pci);
> > > + struct device *dev = pcie->pci->dev;
> > > + u32 index[2];
> > > + int ret;
> > > +
> > > + ret = ls_pcie_host_init(pp);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + pcie->scfg = syscon_regmap_lookup_by_phandle(dev->of_node, "fsl,pcie-scfg");
> > > + if (IS_ERR(pcie->scfg)) {
> > > + ret = PTR_ERR(pcie->scfg);
> > > + dev_err(dev, "No syscfg phandle specified\n");
> > > + pcie->scfg = NULL;
> > > + return ret;
> > > + }
> > > +
> > > + ret = of_property_read_u32_array(dev->of_node, "fsl,pcie-scfg", index, 2);
> > > + if (ret) {
> > > + pcie->scfg = NULL;
> > > + return ret;
> > > + }
> > > +
> > > + pcie->index = index[1];
> > > +
> >
> > The above syscon parsing could be done conditionally during probe itself. There
> > is no need to do it during host_init() time.
> >
> > - Mani
> >
> > > + return ret;
> > > +}
> > > +
> > > 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 dw_pcie_host_ops ls1021a_pcie_host_ops = {
> > > + .host_init = ls1021a_pcie_host_init,
> > > + .pme_turn_off = ls1021a_pcie_send_turnoff_msg,
> > > +};
> > > +
> > > static const struct ls_pcie_drvdata ls1021a_drvdata = {
> > > - .pm_support = false,
> > > + .pm_support = true,
> > > + .ops = &ls1021a_pcie_host_ops,
> > > + .exit_from_l2 = ls1021a_pcie_exit_from_l2,
> > > };
> > >
> > > static const struct ls_pcie_drvdata layerscape_drvdata = {
> > > --
> > > 2.34.1
> > >
> >
> > --
> > மணிவண்ணன் சதாசிவம்
--
மணிவண்ணன் சதாசிவம்
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