linux-kernel - Re: [PATCH v6 2/2] pinctrl: microchip sgpio: use reset driver

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Message-ID: <20211018111231.bawmvre4dqow65dy@soft-dev3-1.localhost>
Date:   Mon, 18 Oct 2021 13:12:31 +0200
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>
CC:     <linus.walleij@...aro.org>, <robh+dt@...nel.org>,
        <lars.povlsen@...rochip.com>, <Steen.Hegelund@...rochip.com>,
        <UNGLinuxDriver@...rochip.com>, <linux-gpio@...r.kernel.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 2/2] pinctrl: microchip sgpio: use reset driver

The 10/18/2021 12:37, Philipp Zabel wrote:

Hi Philipp,
> 
> Hi Horatiu,
> 
> On Mon, 2021-10-18 at 10:57 +0200, Horatiu Vultur wrote:
> > On lan966x platform when the switch gets reseted then also the sgpio
> > gets reseted. The fix for this is to extend also the sgpio driver to
> > call the reset driver which will be reseted only once by the first
> > driver that is probed.
> >
> > Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
> > ---
> >  drivers/pinctrl/pinctrl-microchip-sgpio.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/pinctrl/pinctrl-microchip-sgpio.c b/drivers/pinctrl/pinctrl-microchip-sgpio.c
> > index 072bccdea2a5..78765faa245a 100644
> > --- a/drivers/pinctrl/pinctrl-microchip-sgpio.c
> > +++ b/drivers/pinctrl/pinctrl-microchip-sgpio.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/pinctrl/pinmux.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/property.h>
> > +#include <linux/reset.h>
> >
> >  #include "core.h"
> >  #include "pinconf.h"
> > @@ -803,6 +804,7 @@ static int microchip_sgpio_probe(struct platform_device *pdev)
> >       int div_clock = 0, ret, port, i, nbanks;
> >       struct device *dev = &pdev->dev;
> >       struct fwnode_handle *fwnode;
> > +     struct reset_control *reset;
> >       struct sgpio_priv *priv;
> >       struct clk *clk;
> >       u32 val;
> > @@ -813,6 +815,11 @@ static int microchip_sgpio_probe(struct platform_device *pdev)
> >
> >       priv->dev = dev;
> >
> > +     reset = devm_reset_control_get_optional_shared(&pdev->dev, "switch");
> 
> This is the first GPIO driver that I am aware of that requests a named
> reset control, so I'm still not sure if this should be called "switch"
> instead of "gpio" or just "reset", just in case there is a future model
> where the GPIO controller reset is not shared with the switch reset.

I agree, it is not the best name. But the name "switch" was already used
in DT by sparx5[1], so I just went with this name.

> 
> > +     if (IS_ERR(reset))
> > +             return dev_err_probe(dev, PTR_ERR(reset), "Failed to get reset\n");
> > +     reset_control_reset(reset);
> > +
> >       clk = devm_clk_get(dev, NULL);
> >       if (IS_ERR(clk))
> >               return dev_err_probe(dev, PTR_ERR(clk), "Failed to get clock\n");
> 
> But whichever name you choose, the code is
> 
> Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>
> 
> regards
> Philipp

[1] https://elixir.bootlin.com/linux/v5.15-rc5/source/arch/arm64/boot/dts/microchip/sparx5.dtsi#L307

-- 
/Horatiu