On Thu, Mar 28, 2019 at 09:18:22AM -0500, Bjorn Helgaas wrote:
> On Mon, Mar 25, 2019 at 08:43:19PM +0100, marek.vasut@xxxxxxxxx wrote:
> > From: Kazufumi Ikeda <kaz-ikeda@xxxxxxxxxxxxx>
> >
> > Reestablish the PCIe link very early in the resume process in case it
> > went down to prevent PCI accesses from hanging the bus. Such accesses
> > can happen early in the PCI resume process, as early as the
> > SUSPEND_RESUME_NOIRQ step, thus the link must be reestablished in the
> > driver resume_noirq() callback.
> >
> > Fixes: e015f88c368d ("PCI: rcar: Add support for R-Car H3 to pcie-rcar")
>
> I'm fine with the fix itself, but since e015f88c368d appeared more
> than two years ago in v4.5, the justification for merging this after
> the merge window is a little weak.
>
> Is there a more recent change that exposed this problem? The usual
> situation is that we merged something during the v5.1 merge window
> that caused a regression, and we're now fixing that before v5.1 final.
I do not think that's urgent enough to merge it in one of the -rc* but I
won't speak for the authors - it will trickle back anyway through the
stable mechanism, I just queued it as a fix since that's how it
qualifies.
So postponing it to v5.2 is fine by me, just let me know how it is best
to handle it.
Thanks,
Lorenzo
> Bjorn
>
> > Signed-off-by: Kazufumi Ikeda <kaz-ikeda@xxxxxxxxxxxxx>
> > Signed-off-by: Gaku Inami <gaku.inami.xw@xxxxxxxxxxxxxx>
> > Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
> > [lorenzo.pieralisi@xxxxxxx: reformatted commit log]
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > Reviewed-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> > Acked-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > Cc: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
> > Cc: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> > Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> > Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
> > ---
> > V2: - Use BIT() macro for (1 << n)
> > - Since polling in rcar_pcie_wait_for_dl() uses udelay(), do not
> > add extra changes to this function anymore
> > - Make resume_noirq return early and clean up parenthesis therein
> > V3: - Add missing PMSR register definition, dropped due to patch reshuffling
> > ---
> > drivers/pci/controller/pcie-rcar.c | 21 +++++++++++++++++++++
> > 1 file changed, 21 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
> > index c8febb009454..6a4e435bd35f 100644
> > --- a/drivers/pci/controller/pcie-rcar.c
> > +++ b/drivers/pci/controller/pcie-rcar.c
> > @@ -46,6 +46,7 @@
> >
> > /* Transfer control */
> > #define PCIETCTLR 0x02000
> > +#define DL_DOWN BIT(3)
> > #define CFINIT 1
> > #define PCIETSTR 0x02004
> > #define DATA_LINK_ACTIVE 1
> > @@ -94,6 +95,7 @@
> > #define MACCTLR 0x011058
> > #define SPEED_CHANGE BIT(24)
> > #define SCRAMBLE_DISABLE BIT(27)
> > +#define PMSR 0x01105c
> > #define MACS2R 0x011078
> > #define MACCGSPSETR 0x011084
> > #define SPCNGRSN BIT(31)
> > @@ -1130,6 +1132,7 @@ static int rcar_pcie_probe(struct platform_device *pdev)
> > pcie = pci_host_bridge_priv(bridge);
> >
> > pcie->dev = dev;
> > + platform_set_drvdata(pdev, pcie);
> >
> > err = pci_parse_request_of_pci_ranges(dev, &pcie->resources, NULL);
> > if (err)
> > @@ -1221,10 +1224,28 @@ static int rcar_pcie_probe(struct platform_device *pdev)
> > return err;
> > }
> >
> > +static int rcar_pcie_resume_noirq(struct device *dev)
> > +{
> > + struct rcar_pcie *pcie = dev_get_drvdata(dev);
> > +
> > + if (rcar_pci_read_reg(pcie, PMSR) &&
> > + !(rcar_pci_read_reg(pcie, PCIETCTLR) & DL_DOWN))
> > + return 0;
> > +
> > + /* Re-establish the PCIe link */
> > + rcar_pci_write_reg(pcie, CFINIT, PCIETCTLR);
> > + return rcar_pcie_wait_for_dl(pcie);
> > +}
> > +
> > +static const struct dev_pm_ops rcar_pcie_pm_ops = {
> > + .resume_noirq = rcar_pcie_resume_noirq,
> > +};
> > +
> > static struct platform_driver rcar_pcie_driver = {
> > .driver = {
> > .name = "rcar-pcie",
> > .of_match_table = rcar_pcie_of_match,
> > + .pm = &rcar_pcie_pm_ops,
> > .suppress_bind_attrs = true,
> > },
> > .probe = rcar_pcie_probe,
> > --
> > 2.20.1
> >
