Re: [PATCH v11 04/11] PCI: brcmstb: Add suspend and resume pm_ops

[Florian Fainelli]

On 9/10/2020 12:05 PM, Jim Quinlan wrote:
> On Thu, Sep 10, 2020 at 2:50 PM Rob Herring <robh@xxxxxxxxxx> wrote:
> > On Thu, Sep 10, 2020 at 10:42 AM Jim Quinlan <james.quinlan@xxxxxxxxxxxx> wrote:
> > > On Thu, Sep 10, 2020 at 11:56 AM Rob Herring <robh@xxxxxxxxxx> wrote:
> > > > On Mon, Aug 24, 2020 at 03:30:17PM -0400, Jim Quinlan wrote:
> > > > > From: Jim Quinlan <jquinlan@xxxxxxxxxxxx>
> > > > >
> > > > > 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@xxxxxxxxxxxx>
> > > > > Acked-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> > > > > ---
> > > > >   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.
> >
> > Why not just the 'regular' flavor suspend/resume?
> >
> > Rob
> We must have our PCIe driver suspend last and resume first because our
> current driver turns off/on the power for the EPs.  Note that this
> code isn't in the driver as we are still figuring out a way to make it
> upstreamable.

The suspend/resume ordering should be guaranteed by the Linux device 
driver model though if not, this is a bug that ought to be fixed. The 
PCI bridge sits at the top of the pci_device list and all EPs should be 
child devices, so the suspend order should be from EPs down to the 
bridge, and the resume the converse.
--
Florian