linux-kernel - Re: [PATCH 1/3] net: davicom: dm9000: switch to using gpiod API

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Message-ID: <Y3ernUQfdWMBtO9z@google.com>
Date:   Fri, 18 Nov 2022 07:58:21 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] net: davicom: dm9000: switch to using gpiod API

Hi Paul,

On Fri, Nov 18, 2022 at 03:33:44PM +0000, Paul Cercueil wrote:
> Hi Dmitry,
> 
> Le mar. 6 sept. 2022 à 13:49:20 -0700, Dmitry Torokhov
> <dmitry.torokhov@...il.com> a écrit :
> > This patch switches the driver away from legacy gpio/of_gpio API to
> > gpiod API, and removes use of of_get_named_gpio_flags() which I want to
> > make private to gpiolib.
> > 
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > ---
> >  drivers/net/ethernet/davicom/dm9000.c | 26 ++++++++++++++------------
> >  1 file changed, 14 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/davicom/dm9000.c
> > b/drivers/net/ethernet/davicom/dm9000.c
> > index 77229e53b04e..c85a6ebd79fc 100644
> > --- a/drivers/net/ethernet/davicom/dm9000.c
> > +++ b/drivers/net/ethernet/davicom/dm9000.c
> > @@ -28,8 +28,7 @@
> >  #include <linux/irq.h>
> >  #include <linux/slab.h>
> >  #include <linux/regulator/consumer.h>
> > -#include <linux/gpio.h>
> > -#include <linux/of_gpio.h>
> > +#include <linux/gpio/consumer.h>
> > 
> >  #include <asm/delay.h>
> >  #include <asm/irq.h>
> > @@ -1421,8 +1420,7 @@ dm9000_probe(struct platform_device *pdev)
> >  	int iosize;
> >  	int i;
> >  	u32 id_val;
> > -	int reset_gpios;
> > -	enum of_gpio_flags flags;
> > +	struct gpio_desc *reset_gpio;
> >  	struct regulator *power;
> >  	bool inv_mac_addr = false;
> >  	u8 addr[ETH_ALEN];
> > @@ -1442,20 +1440,24 @@ dm9000_probe(struct platform_device *pdev)
> >  		dev_dbg(dev, "regulator enabled\n");
> >  	}
> > 
> > -	reset_gpios = of_get_named_gpio_flags(dev->of_node, "reset-gpios", 0,
> > -					      &flags);
> > -	if (gpio_is_valid(reset_gpios)) {
> > -		ret = devm_gpio_request_one(dev, reset_gpios, flags,
> > -					    "dm9000_reset");
> > +	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> > +	ret = PTR_ERR_OR_ZERO(reset_gpio);
> > +	if (ret) {
> > +		dev_err(dev, "failed to request reset gpio: %d\n", ret);
> > +		goto out_regulator_disable;
> > +	}
> > +
> > +	if (reset_gpio) {
> > +		ret = gpiod_set_consumer_name(reset_gpio, "dm9000_reset");
> >  		if (ret) {
> > -			dev_err(dev, "failed to request reset gpio %d: %d\n",
> > -				reset_gpios, ret);
> > +			dev_err(dev, "failed to set reset gpio name: %d\n",
> > +				ret);
> >  			goto out_regulator_disable;
> >  		}
> > 
> >  		/* According to manual PWRST# Low Period Min 1ms */
> >  		msleep(2);
> > -		gpio_set_value(reset_gpios, 1);
> > +		gpiod_set_value_cansleep(reset_gpio, 0);
> 
> Why is that 1 magically turned into a 0?

Because gpiod uses logical states (think active/inactive), not absolute
ones. Here we are deasserting the reset line.

> 
> On my CI20 board I can't get the DM9000 chip to probe correctly with this
> patch (it fails to read the ID).
> If I revert this patch then everything works fine.

Sorry, it is my fault of course: I missed that board has incorrect
annotation for the reset line. I will send out the patch below
(formatted properly of course):

diff --git a/arch/mips/boot/dts/ingenic/ci20.dts b/arch/mips/boot/dts/ingenic/ci20.dts
index 37c46720c719..f38c39572a9e 100644
--- a/arch/mips/boot/dts/ingenic/ci20.dts
+++ b/arch/mips/boot/dts/ingenic/ci20.dts
@@ -438,7 +438,7 @@ dm9000@6 {
 		ingenic,nemc-tAW = <50>;
 		ingenic,nemc-tSTRV = <100>;
 
-		reset-gpios = <&gpf 12 GPIO_ACTIVE_HIGH>;
+		reset-gpios = <&gpf 12 GPIO_ACTIVE_LOW>;
 		vcc-supply = <&eth0_power>;
 
 		interrupt-parent = <&gpe>;


Thanks.

-- 
Dmitry