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

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Message-ID: <6f46c5ab7458e1368abfeb8dee6e24271f39d236.camel@pengutronix.de>
Date:   Mon, 18 Oct 2021 12:37:19 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>,
        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

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.

> +	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