linux-kernel - Re: [PATCH v11 04/11] PCI: brcmstb: Add suspend and resume pm

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Date:   Thu, 10 Sep 2020 12:42:30 -0400
From:   Jim Quinlan <james.quinlan@...adcom.com>
To:     Rob Herring <robh@...nel.org>
Cc:     "open list:PCI NATIVE HOST BRIDGE AND ENDPOINT DRIVERS" 
        <linux-pci@...r.kernel.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Christoph Hellwig <hch@....de>,
        Robin Murphy <robin.murphy@....com>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 04/11] PCI: brcmstb: Add suspend and resume pm_ops

On Thu, Sep 10, 2020 at 11:56 AM Rob Herring <robh@...nel.org> wrote:
>
> On Mon, Aug 24, 2020 at 03:30:17PM -0400, Jim Quinlan wrote:
> > From: Jim Quinlan <jquinlan@...adcom.com>
> >
> > Broadcom Set-top (BrcmSTB) boards typically support S2, S3, and S5 suspend
> > and resume.  Now the PCIe driver may do so as well.
> >
> > Signed-off-by: Jim Quinlan <jquinlan@...adcom.com>
> > Acked-by: Florian Fainelli <f.fainelli@...il.com>
> > ---
> >  drivers/pci/controller/pcie-brcmstb.c | 47 +++++++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index c2b3d2946a36..3d588ab7a6dd 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -978,6 +978,47 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
> >       brcm_pcie_bridge_sw_init_set(pcie, 1);
> >  }
> >
> > +static int brcm_pcie_suspend(struct device *dev)
> > +{
> > +     struct brcm_pcie *pcie = dev_get_drvdata(dev);
> > +
> > +     brcm_pcie_turn_off(pcie);
> > +     clk_disable_unprepare(pcie->clk);
> > +
> > +     return 0;
> > +}
> > +
> > +static int brcm_pcie_resume(struct device *dev)
> > +{
> > +     struct brcm_pcie *pcie = dev_get_drvdata(dev);
> > +     void __iomem *base;
> > +     u32 tmp;
> > +     int ret;
> > +
> > +     base = pcie->base;
> > +     clk_prepare_enable(pcie->clk);
> > +
> > +     /* Take bridge out of reset so we can access the SERDES reg */
> > +     brcm_pcie_bridge_sw_init_set(pcie, 0);
> > +
> > +     /* SERDES_IDDQ = 0 */
> > +     tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> > +     u32p_replace_bits(&tmp, 0, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
> > +     writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> > +
> > +     /* wait for serdes to be stable */
> > +     udelay(100);
>
> Really needs to be a spinloop?
>
> > +
> > +     ret = brcm_pcie_setup(pcie);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (pcie->msi)
> > +             brcm_msi_set_regs(pcie->msi);
> > +
> > +     return 0;
> > +}
> > +
> >  static void __brcm_pcie_remove(struct brcm_pcie *pcie)
> >  {
> >       brcm_msi_remove(pcie);
> > @@ -1087,12 +1128,18 @@ static int brcm_pcie_probe(struct platform_device *pdev)
> >
> >  MODULE_DEVICE_TABLE(of, brcm_pcie_match);
> >
> > +static const struct dev_pm_ops brcm_pcie_pm_ops = {
> > +     .suspend_noirq = brcm_pcie_suspend,
> > +     .resume_noirq = brcm_pcie_resume,
>
> Why do you need interrupts disabled? There's 39 cases of .suspend_noirq
> and 1352 of .suspend in the tree.

I will test switching this to  suspend_late/resume_early.

Thanks,
Jim Quinlan
Broadcom STB
>
> Is doing a clk unprepare even safe in .suspend_noirq? IIRC,
> prepare/unprepare can sleep.
>
> > +};
> > +
> >  static struct platform_driver brcm_pcie_driver = {
> >       .probe = brcm_pcie_probe,
> >       .remove = brcm_pcie_remove,
> >       .driver = {
> >               .name = "brcm-pcie",
> >               .of_match_table = brcm_pcie_match,
> > +             .pm = &brcm_pcie_pm_ops,
> >       },
> >  };
> >  module_platform_driver(brcm_pcie_driver);
> > --
> > 2.17.1
> >

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