Re: [PATCH 07/15] PCI: brcmstb: Add control of rescal reset

[Jim Quinlan]

On Wed, May 20, 2020 at 3:27 AM Philipp Zabel <pza@xxxxxxxxxxxxxx> wrote:
>
> Hi Jim,
>
> On Tue, May 19, 2020 at 04:34:05PM -0400, Jim Quinlan wrote:
> > From: Jim Quinlan <jquinlan@xxxxxxxxxxxx>
> >
> > Some STB chips have a special purpose reset controller named
> > RESCAL (reset calibration).  This commit adds the control
> > of RESCAL as well as the ability to start and stop its
> > operation for PCIe HW.
> >
> > Signed-off-by: Jim Quinlan <jquinlan@xxxxxxxxxxxx>
> > ---
> >  drivers/pci/controller/pcie-brcmstb.c | 81 ++++++++++++++++++++++++++-
> >  1 file changed, 80 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index 2c470104ba38..0787e8f6f7e5 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> [...]
> > @@ -1100,6 +1164,21 @@ static int brcm_pcie_probe(struct platform_device *pdev)
> >               dev_err(&pdev->dev, "could not enable clock\n");
> >               return ret;
> >       }
> > +     pcie->rescal = devm_reset_control_get_shared(&pdev->dev, "rescal");
> > +     if (IS_ERR(pcie->rescal)) {
> > +             if (PTR_ERR(pcie->rescal) == -EPROBE_DEFER)
> > +                     return -EPROBE_DEFER;
> > +             pcie->rescal = NULL;
>
> This is effectively an optional reset control, so it is better to use:
> â
>         pcie->rescal = devm_reset_control_get_optional_shared(&pdev->dev,
>                                                               "rescal");â
>         if (IS_ERR(pcie->rescal))
>                 return PTR_ERR(pcie->rescal);
>
> > +     } else {
> > +             ret = reset_control_deassert(pcie->rescal);
> > +             if (ret)
> > +                     dev_err(&pdev->dev, "failed to deassert 'rescal'\n");
> > +     }
>
> reset_control_* can handle rstc == NULL parameters for optional reset
> controls, so this can be done unconditionally:
>
>         ret = reset_control_deassert(pcie->rescal);â
>         if (ret)â
>                 dev_err(&pdev->dev, "failed to deassert 'rescal'\n");â
>
> Is rescal handled by the reset-brcmstb-rescal driver? Since that only
> implements the .reset op, I would expect reset_control_reset() here.
Where exactly?  "reset.h" says that "Calling reset_control_rese()t is
not allowed on a shared reset control." so I'm not sure why  you would
want me to invoke it.
> Otherwise this looks like it'd be missing a reset_control_assert in
> remove.
I can add this.
Thanks,
Jim
>
> regards
> Philipp