linux-kernel - Re: [PATCH v2 04/12] PCI: brcmstb: Use swinit reset if available

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Message-ID: <CA+-6iNynwxcBAbRQ18TfJXwCctf+Ok7DnFyjgv4wNasX9MjV1Q@mail.gmail.com>
Date: Fri, 5 Jul 2024 13:46:12 -0400
From: Jim Quinlan <james.quinlan@...adcom.com>
To: Stanimir Varbanov <svarbanov@...e.de>
Cc: linux-pci@...r.kernel.org, Nicolas Saenz Julienne <nsaenz@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Lorenzo Pieralisi <lorenzo.pieralisi@....com>, 
	Cyril Brulebois <kibi@...ian.org>, bcm-kernel-feedback-list@...adcom.com, 
	jim2101024@...il.com, Florian Fainelli <florian.fainelli@...adcom.com>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kw@...ux.com>, 
	Rob Herring <robh@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	"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 v2 04/12] PCI: brcmstb: Use swinit reset if available

On Thu, Jul 4, 2024 at 8:56 AM Stanimir Varbanov <svarbanov@...e.de> wrote:
>
> Hi Jim,
>
> On 7/3/24 21:02, Jim Quinlan wrote:
> > The 7712 SOC adds a software init reset device for the PCIe HW.
> > If found in the DT node, use it.
> >
> > Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> > ---
> >  drivers/pci/controller/pcie-brcmstb.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index 4104c3668fdb..69926ee5c961 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -266,6 +266,7 @@ struct brcm_pcie {
> >       struct reset_control    *rescal;
> >       struct reset_control    *perst_reset;
> >       struct reset_control    *bridge;
> > +     struct reset_control    *swinit;
> >       int                     num_memc;
> >       u64                     memc_size[PCIE_BRCM_MAX_MEMC];
> >       u32                     hw_rev;
> > @@ -1626,6 +1627,13 @@ static int brcm_pcie_probe(struct platform_device *pdev)
> >               dev_err(&pdev->dev, "could not enable clock\n");
> >               return ret;
> >       }
> > +
> > +     pcie->swinit = devm_reset_control_get_optional_exclusive(&pdev->dev, "swinit");
> > +     if (IS_ERR(pcie->swinit)) {
> > +             ret = dev_err_probe(&pdev->dev, PTR_ERR(pcie->swinit),
> > +                                 "failed to get 'swinit' reset\n");
> > +             goto clk_out;
> > +     }
> >       pcie->rescal = devm_reset_control_get_optional_shared(&pdev->dev, "rescal");
> >       if (IS_ERR(pcie->rescal)) {
> >               ret = PTR_ERR(pcie->rescal);
> > @@ -1637,6 +1645,17 @@ static int brcm_pcie_probe(struct platform_device *pdev)
> >               goto clk_out;
> >       }
> >
> > +     ret = reset_control_assert(pcie->swinit);
> > +     if (ret) {
> > +             dev_err_probe(&pdev->dev, ret, "could not assert reset 'swinit'\n");
> > +             goto clk_out;
> > +     }
> > +     ret = reset_control_deassert(pcie->swinit);
> > +     if (ret) {
> > +             dev_err(&pdev->dev, "could not de-assert reset 'swinit' after asserting\n");
> > +             goto clk_out;
> > +     }
>
> why not call reset_control_reset(pcie->swinit) directly?
Hi Stan,

There is no reset_control_reset() method defined for reset-brcmstb.c.
The only reason I can
think of for this is that it allows the callers of assert/deassert to
insert a delay if desired.

Regards,
Jim Quinlan
Broadcom STB/CM
>
> ~Stan
> > +
> >       ret = reset_control_reset(pcie->rescal);
> >       if (ret) {
> >               dev_err(&pdev->dev, "failed to deassert 'rescal'\n");

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