[PATCH 0/2] ieee802154: mcr20a: clean and improve the driver

[PATCH 0/2] ieee802154: mcr20a: clean and improve the driver

[Xue Liu]

The first patch replaces the magic numer with defined constants to make
the IRQ state more clearly.

The second patch removes the struct mcr20a_platform_data since it is not
widely used. Meanwhile gpiod family APIs are used to handle reset pin.

Xue Liu (2):
  ieee802154: mcr20a: Replace magic number with constants
  ieee802154: mcr20a: Remove struct mcr20a_platform_data

 drivers/net/ieee802154/mcr20a.c | 72 ++++++++-------------------------
 1 file changed, 17 insertions(+), 55 deletions(-)

-- 
2.17.0

[PATCH 1/2] ieee802154: mcr20a: Replace magic number with constants

[Xue Liu]

The combination of defined constants are used to present the
state of IRQ so the magic numbers has been replaced.

This is a simple coding style change which should have no impact on
runtime code execution.

Signed-off-by: Xue Liu <liuxuenetmail@gmail.com>
---
 drivers/net/ieee802154/mcr20a.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
index e428277781ac..04891429a554 100644
--- a/drivers/net/ieee802154/mcr20a.c
+++ b/drivers/net/ieee802154/mcr20a.c
@@ -903,19 +903,19 @@ mcr20a_irq_clean_complete(void *context)
 
 	switch (seq_state) {
 	/* TX IRQ, RX IRQ and SEQ IRQ */
-	case (0x03):
+	case (DAR_IRQSTS1_TXIRQ | DAR_IRQSTS1_SEQIRQ):
 		if (lp->is_tx) {
 			lp->is_tx = 0;
 			dev_dbg(printdev(lp), "TX is done. No ACK\n");
 			mcr20a_handle_tx_complete(lp);
 		}
 		break;
-	case (0x05):
+	case (DAR_IRQSTS1_RXIRQ | DAR_IRQSTS1_SEQIRQ):
 			/* rx is starting */
 			dev_dbg(printdev(lp), "RX is starting\n");
 			mcr20a_handle_rx(lp);
 		break;
-	case (0x07):
+	case (DAR_IRQSTS1_RXIRQ | DAR_IRQSTS1_TXIRQ | DAR_IRQSTS1_SEQIRQ):
 		if (lp->is_tx) {
 			/* tx is done */
 			lp->is_tx = 0;
@@ -927,7 +927,7 @@ mcr20a_irq_clean_complete(void *context)
 			mcr20a_handle_rx(lp);
 		}
 		break;
-	case (0x01):
+	case (DAR_IRQSTS1_SEQIRQ):
 		if (lp->is_tx) {
 			dev_dbg(printdev(lp), "TX is starting\n");
 			mcr20a_handle_tx(lp);
-- 
2.17.0

Re: [PATCH 1/2] ieee802154: mcr20a: Replace magic number with constants

[Stefan Schmidt]

Hello Xue.

On 31/08/2018 23:46, Xue Liu wrote:
> The combination of defined constants are used to present the
> state of IRQ so the magic numbers has been replaced.
> 
> This is a simple coding style change which should have no impact on
> runtime code execution.
> 
> Signed-off-by: Xue Liu <liuxuenetmail@gmail.com>
> ---
>  drivers/net/ieee802154/mcr20a.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
> index e428277781ac..04891429a554 100644
> --- a/drivers/net/ieee802154/mcr20a.c
> +++ b/drivers/net/ieee802154/mcr20a.c
> @@ -903,19 +903,19 @@ mcr20a_irq_clean_complete(void *context)
>  
>  	switch (seq_state) {
>  	/* TX IRQ, RX IRQ and SEQ IRQ */
> -	case (0x03):
> +	case (DAR_IRQSTS1_TXIRQ | DAR_IRQSTS1_SEQIRQ):
>  		if (lp->is_tx) {
>  			lp->is_tx = 0;
>  			dev_dbg(printdev(lp), "TX is done. No ACK\n");
>  			mcr20a_handle_tx_complete(lp);
>  		}
>  		break;
> -	case (0x05):
> +	case (DAR_IRQSTS1_RXIRQ | DAR_IRQSTS1_SEQIRQ):
>  			/* rx is starting */
>  			dev_dbg(printdev(lp), "RX is starting\n");
>  			mcr20a_handle_rx(lp);
>  		break;
> -	case (0x07):
> +	case (DAR_IRQSTS1_RXIRQ | DAR_IRQSTS1_TXIRQ | DAR_IRQSTS1_SEQIRQ):
>  		if (lp->is_tx) {
>  			/* tx is done */
>  			lp->is_tx = 0;
> @@ -927,7 +927,7 @@ mcr20a_irq_clean_complete(void *context)
>  			mcr20a_handle_rx(lp);
>  		}
>  		break;
> -	case (0x01):
> +	case (DAR_IRQSTS1_SEQIRQ):
>  		if (lp->is_tx) {
>  			dev_dbg(printdev(lp), "TX is starting\n");
>  			mcr20a_handle_tx(lp);
> 

This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

I decided to put this into wpan directly as it clearly is cleanup
material. The second patch will need to go through wpan-next though.

regards
Stefan Schmidt

[PATCH 2/2] ieee802154: mcr20a: Remove struct mcr20a_platform_data

[Xue Liu]

The struct mcr20a_platform_data is uesed only in probe function
and it holds only one member. So it is not necessary to reserve it.

Using gpiod family API to handle reset pin.

Signed-off-by: Xue Liu <liuxuenetmail@gmail.com>
---
 drivers/net/ieee802154/mcr20a.c | 64 +++++++--------------------------
 1 file changed, 13 insertions(+), 51 deletions(-)

diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
index 04891429a554..44de81e5f140 100644
--- a/drivers/net/ieee802154/mcr20a.c
+++ b/drivers/net/ieee802154/mcr20a.c
@@ -132,11 +132,6 @@ static const struct reg_sequence mar20a_iar_overwrites[] = {
 };
 
 #define MCR20A_VALID_CHANNELS (0x07FFF800)
-
-struct mcr20a_platform_data {
-	int rst_gpio;
-};
-
 #define MCR20A_MAX_BUF		(127)
 
 #define printdev(X) (&X->spi->dev)
@@ -412,7 +407,6 @@ struct mcr20a_local {
 	struct spi_device *spi;
 
 	struct ieee802154_hw *hw;
-	struct mcr20a_platform_data *pdata;
 	struct regmap *regmap_dar;
 	struct regmap *regmap_iar;
 
@@ -976,20 +970,6 @@ static irqreturn_t mcr20a_irq_isr(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-static int mcr20a_get_platform_data(struct spi_device *spi,
-				    struct mcr20a_platform_data *pdata)
-{
-	int ret = 0;
-
-	if (!spi->dev.of_node)
-		return -EINVAL;
-
-	pdata->rst_gpio = of_get_named_gpio(spi->dev.of_node, "rst_b-gpio", 0);
-	dev_dbg(&spi->dev, "rst_b-gpio: %d\n", pdata->rst_gpio);
-
-	return ret;
-}
-
 static void mcr20a_hw_setup(struct mcr20a_local *lp)
 {
 	u8 i;
@@ -1249,7 +1229,7 @@ mcr20a_probe(struct spi_device *spi)
 {
 	struct ieee802154_hw *hw;
 	struct mcr20a_local *lp;
-	struct mcr20a_platform_data *pdata;
+	struct gpio_desc *rst_b;
 	int irq_type;
 	int ret = -ENOMEM;
 
@@ -1260,48 +1240,32 @@ mcr20a_probe(struct spi_device *spi)
 		return -EINVAL;
 	}
 
-	pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);
-	if (!pdata)
-		return -ENOMEM;
-
-	/* set mcr20a platform data */
-	ret = mcr20a_get_platform_data(spi, pdata);
-	if (ret < 0) {
-		dev_crit(&spi->dev, "mcr20a_get_platform_data failed.\n");
-		goto free_pdata;
-	}
-
-	/* init reset gpio */
-	if (gpio_is_valid(pdata->rst_gpio)) {
-		ret = devm_gpio_request_one(&spi->dev, pdata->rst_gpio,
-					    GPIOF_OUT_INIT_HIGH, "reset");
-		if (ret)
-			goto free_pdata;
+	rst_b = devm_gpiod_get(&spi->dev, "rst_b", GPIOD_OUT_HIGH);
+	if (IS_ERR(rst_b)) {
+		ret = PTR_ERR(rst_b);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&spi->dev, "Failed to get 'rst_b' gpio: %d", ret);
+		return ret;
 	}
 
 	/* reset mcr20a */
-	if (gpio_is_valid(pdata->rst_gpio)) {
-		usleep_range(10, 20);
-		gpio_set_value_cansleep(pdata->rst_gpio, 0);
-		usleep_range(10, 20);
-		gpio_set_value_cansleep(pdata->rst_gpio, 1);
-		usleep_range(120, 240);
-	}
+	usleep_range(10, 20);
+	gpiod_set_value_cansleep(rst_b, 1);
+	usleep_range(10, 20);
+	gpiod_set_value_cansleep(rst_b, 0);
+	usleep_range(120, 240);
 
 	/* allocate ieee802154_hw and private data */
 	hw = ieee802154_alloc_hw(sizeof(*lp), &mcr20a_hw_ops);
 	if (!hw) {
 		dev_crit(&spi->dev, "ieee802154_alloc_hw failed\n");
-		ret = -ENOMEM;
-		goto free_pdata;
+		return ret;
 	}
 
 	/* init mcr20a local data */
 	lp = hw->priv;
 	lp->hw = hw;
 	lp->spi = spi;
-	lp->spi->dev.platform_data = pdata;
-	lp->pdata = pdata;
 
 	/* init ieee802154_hw */
 	hw->parent = &spi->dev;
@@ -1370,8 +1334,6 @@ mcr20a_probe(struct spi_device *spi)
 
 free_dev:
 	ieee802154_free_hw(lp->hw);
-free_pdata:
-	kfree(pdata);
 
 	return ret;
 }
-- 
2.17.0

Re: [PATCH 2/2] ieee802154: mcr20a: Remove struct mcr20a_platform_data

[Stefan Schmidt]

Hello Xue.

On 31/08/2018 23:46, Xue Liu wrote:
> The struct mcr20a_platform_data is uesed only in probe function
> and it holds only one member. So it is not necessary to reserve it.
> 
> Using gpiod family API to handle reset pin.
> 
> Signed-off-by: Xue Liu <liuxuenetmail@gmail.com>
> ---
>  drivers/net/ieee802154/mcr20a.c | 64 +++++++--------------------------
>  1 file changed, 13 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
> index 04891429a554..44de81e5f140 100644
> --- a/drivers/net/ieee802154/mcr20a.c
> +++ b/drivers/net/ieee802154/mcr20a.c
> @@ -132,11 +132,6 @@ static const struct reg_sequence mar20a_iar_overwrites[] = {
>  };
>  
>  #define MCR20A_VALID_CHANNELS (0x07FFF800)
> -
> -struct mcr20a_platform_data {
> -	int rst_gpio;
> -};
> -
>  #define MCR20A_MAX_BUF		(127)
>  
>  #define printdev(X) (&X->spi->dev)
> @@ -412,7 +407,6 @@ struct mcr20a_local {
>  	struct spi_device *spi;
>  
>  	struct ieee802154_hw *hw;
> -	struct mcr20a_platform_data *pdata;
>  	struct regmap *regmap_dar;
>  	struct regmap *regmap_iar;
>  
> @@ -976,20 +970,6 @@ static irqreturn_t mcr20a_irq_isr(int irq, void *data)
>  	return IRQ_HANDLED;
>  }
>  
> -static int mcr20a_get_platform_data(struct spi_device *spi,
> -				    struct mcr20a_platform_data *pdata)
> -{
> -	int ret = 0;
> -
> -	if (!spi->dev.of_node)
> -		return -EINVAL;
> -
> -	pdata->rst_gpio = of_get_named_gpio(spi->dev.of_node, "rst_b-gpio", 0);
> -	dev_dbg(&spi->dev, "rst_b-gpio: %d\n", pdata->rst_gpio);
> -
> -	return ret;
> -}
> -
>  static void mcr20a_hw_setup(struct mcr20a_local *lp)
>  {
>  	u8 i;
> @@ -1249,7 +1229,7 @@ mcr20a_probe(struct spi_device *spi)
>  {
>  	struct ieee802154_hw *hw;
>  	struct mcr20a_local *lp;
> -	struct mcr20a_platform_data *pdata;
> +	struct gpio_desc *rst_b;
>  	int irq_type;
>  	int ret = -ENOMEM;
>  
> @@ -1260,48 +1240,32 @@ mcr20a_probe(struct spi_device *spi)
>  		return -EINVAL;
>  	}
>  
> -	pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);
> -	if (!pdata)
> -		return -ENOMEM;
> -
> -	/* set mcr20a platform data */
> -	ret = mcr20a_get_platform_data(spi, pdata);
> -	if (ret < 0) {
> -		dev_crit(&spi->dev, "mcr20a_get_platform_data failed.\n");
> -		goto free_pdata;
> -	}
> -
> -	/* init reset gpio */
> -	if (gpio_is_valid(pdata->rst_gpio)) {
> -		ret = devm_gpio_request_one(&spi->dev, pdata->rst_gpio,
> -					    GPIOF_OUT_INIT_HIGH, "reset");
> -		if (ret)
> -			goto free_pdata;
> +	rst_b = devm_gpiod_get(&spi->dev, "rst_b", GPIOD_OUT_HIGH);

I am a bit confused about the pin name here. When using
of_get_named_gpio() the name is "rst_b-gpio" which is the same I see
referenced in the devicetree bindings file.

When switching to devm_gpiod_get() the name is shortened to "rst_b".
Does the gpiod API implicitly add a -gpio to the name when searching for
it in the dst?

The reason I ask is that I would want to avoid a name change of the
property. That would break the dts bindings already in place.

> +	if (IS_ERR(rst_b)) {
> +		ret = PTR_ERR(rst_b);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(&spi->dev, "Failed to get 'rst_b' gpio: %d", ret);
> +		return ret;
>  	}
>  
>  	/* reset mcr20a */
> -	if (gpio_is_valid(pdata->rst_gpio)) {
> -		usleep_range(10, 20);
> -		gpio_set_value_cansleep(pdata->rst_gpio, 0);
> -		usleep_range(10, 20);
> -		gpio_set_value_cansleep(pdata->rst_gpio, 1);
> -		usleep_range(120, 240);
> -	}
> +	usleep_range(10, 20);
> +	gpiod_set_value_cansleep(rst_b, 1);
> +	usleep_range(10, 20);
> +	gpiod_set_value_cansleep(rst_b, 0);
> +	usleep_range(120, 240);

With your change you reversing the setting from ->0->1 to ->1->0. Is the
gpiod API reverse here or did you made a copy and paste mistake? :-)

>  
>  	/* allocate ieee802154_hw and private data */
>  	hw = ieee802154_alloc_hw(sizeof(*lp), &mcr20a_hw_ops);
>  	if (!hw) {
>  		dev_crit(&spi->dev, "ieee802154_alloc_hw failed\n");
> -		ret = -ENOMEM;
> -		goto free_pdata;
> +		return ret;
>  	}
>  
>  	/* init mcr20a local data */
>  	lp = hw->priv;
>  	lp->hw = hw;
>  	lp->spi = spi;
> -	lp->spi->dev.platform_data = pdata;
> -	lp->pdata = pdata;
>  
>  	/* init ieee802154_hw */
>  	hw->parent = &spi->dev;
> @@ -1370,8 +1334,6 @@ mcr20a_probe(struct spi_device *spi)
>  
>  free_dev:
>  	ieee802154_free_hw(lp->hw);
> -free_pdata:
> -	kfree(pdata);
>  
>  	return ret;
>  }
> 

The rest looks good to me and I like that we can get rid of all the
boiler code associated with the pdata.

If you could clarify (and potentially fix) the two points I raised I
would be happy to apply this.

regards
Stefan Schmidt

Re: [PATCH 2/2] ieee802154: mcr20a: Remove struct mcr20a_platform_data

[Xue Liu]

Hi Stefan,
On Thu, 27 Sep 2018 at 17:44, Stefan Schmidt <stefan@datenfreihafen.org> wrote:
>
> Hello Xue.
>
> On 31/08/2018 23:46, Xue Liu wrote:
> > The struct mcr20a_platform_data is uesed only in probe function
> > and it holds only one member. So it is not necessary to reserve it.
> >
> > Using gpiod family API to handle reset pin.
> >
> > Signed-off-by: Xue Liu <liuxuenetmail@gmail.com>
> > ---
> >  drivers/net/ieee802154/mcr20a.c | 64 +++++++--------------------------
> >  1 file changed, 13 insertions(+), 51 deletions(-)
> >
> > diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
> > index 04891429a554..44de81e5f140 100644
> > --- a/drivers/net/ieee802154/mcr20a.c
> > +++ b/drivers/net/ieee802154/mcr20a.c
> > @@ -132,11 +132,6 @@ static const struct reg_sequence mar20a_iar_overwrites[] = {
> >  };
> >
> >  #define MCR20A_VALID_CHANNELS (0x07FFF800)
> > -
> > -struct mcr20a_platform_data {
> > -     int rst_gpio;
> > -};
> > -
> >  #define MCR20A_MAX_BUF               (127)
> >
> >  #define printdev(X) (&X->spi->dev)
> > @@ -412,7 +407,6 @@ struct mcr20a_local {
> >       struct spi_device *spi;
> >
> >       struct ieee802154_hw *hw;
> > -     struct mcr20a_platform_data *pdata;
> >       struct regmap *regmap_dar;
> >       struct regmap *regmap_iar;
> >
> > @@ -976,20 +970,6 @@ static irqreturn_t mcr20a_irq_isr(int irq, void *data)
> >       return IRQ_HANDLED;
> >  }
> >
> > -static int mcr20a_get_platform_data(struct spi_device *spi,
> > -                                 struct mcr20a_platform_data *pdata)
> > -{
> > -     int ret = 0;
> > -
> > -     if (!spi->dev.of_node)
> > -             return -EINVAL;
> > -
> > -     pdata->rst_gpio = of_get_named_gpio(spi->dev.of_node, "rst_b-gpio", 0);
> > -     dev_dbg(&spi->dev, "rst_b-gpio: %d\n", pdata->rst_gpio);
> > -
> > -     return ret;
> > -}
> > -
> >  static void mcr20a_hw_setup(struct mcr20a_local *lp)
> >  {
> >       u8 i;
> > @@ -1249,7 +1229,7 @@ mcr20a_probe(struct spi_device *spi)
> >  {
> >       struct ieee802154_hw *hw;
> >       struct mcr20a_local *lp;
> > -     struct mcr20a_platform_data *pdata;
> > +     struct gpio_desc *rst_b;
> >       int irq_type;
> >       int ret = -ENOMEM;
> >
> > @@ -1260,48 +1240,32 @@ mcr20a_probe(struct spi_device *spi)
> >               return -EINVAL;
> >       }
> >
> > -     pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);
> > -     if (!pdata)
> > -             return -ENOMEM;
> > -
> > -     /* set mcr20a platform data */
> > -     ret = mcr20a_get_platform_data(spi, pdata);
> > -     if (ret < 0) {
> > -             dev_crit(&spi->dev, "mcr20a_get_platform_data failed.\n");
> > -             goto free_pdata;
> > -     }
> > -
> > -     /* init reset gpio */
> > -     if (gpio_is_valid(pdata->rst_gpio)) {
> > -             ret = devm_gpio_request_one(&spi->dev, pdata->rst_gpio,
> > -                                         GPIOF_OUT_INIT_HIGH, "reset");
> > -             if (ret)
> > -                     goto free_pdata;
> > +     rst_b = devm_gpiod_get(&spi->dev, "rst_b", GPIOD_OUT_HIGH);
>
> I am a bit confused about the pin name here. When using
> of_get_named_gpio() the name is "rst_b-gpio" which is the same I see
> referenced in the devicetree bindings file.
>
> When switching to devm_gpiod_get() the name is shortened to "rst_b".
> Does the gpiod API implicitly add a -gpio to the name when searching for
> it in the dst?
>
Yes. The function calling tree is shown below:
--> devm_gpiod_get()
    --> __gpiod_get_index()
         --> of_find_gpio()
The definition of function of_find_gpio() is here
https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib-of.c#L231.
The definition of struct gpio_suffixes is here
https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.h#L95.
You can see that the suffix "gpio" or "gpios" is automatically added
when it is looking for the name of gpio in the device tree.

> The reason I ask is that I would want to avoid a name change of the
> property. That would break the dts bindings already in place.
>
We don't need to change the dts bindings.

> > +     if (IS_ERR(rst_b)) {
> > +             ret = PTR_ERR(rst_b);
> > +             if (ret != -EPROBE_DEFER)
> > +                     dev_err(&spi->dev, "Failed to get 'rst_b' gpio: %d", ret);
> > +             return ret;
> >       }
> >
> >       /* reset mcr20a */
> > -     if (gpio_is_valid(pdata->rst_gpio)) {
> > -             usleep_range(10, 20);
> > -             gpio_set_value_cansleep(pdata->rst_gpio, 0);
> > -             usleep_range(10, 20);
> > -             gpio_set_value_cansleep(pdata->rst_gpio, 1);
> > -             usleep_range(120, 240);
> > -     }
> > +     usleep_range(10, 20);
> > +     gpiod_set_value_cansleep(rst_b, 1);
> > +     usleep_range(10, 20);
> > +     gpiod_set_value_cansleep(rst_b, 0);
> > +     usleep_range(120, 240);
>
> With your change you reversing the setting from ->0->1 to ->1->0. Is the
> gpiod API reverse here or did you made a copy and paste mistake? :-)
>
I am afraid both of assumptions are wrong here. The new GPIO
descriptor consumer interface uses *logical* value.
It means 0 and 1 denote GPIO deassertion and assertion. The property
of rst_b is GPIO_ACTIVE_LOW. So the value 1
means low in physical line and the value 0 means high.

Please reference
https://www.kernel.org/doc/Documentation/gpio/consumer.txt for more
information.

> >
> >       /* allocate ieee802154_hw and private data */
> >       hw = ieee802154_alloc_hw(sizeof(*lp), &mcr20a_hw_ops);
> >       if (!hw) {
> >               dev_crit(&spi->dev, "ieee802154_alloc_hw failed\n");
> > -             ret = -ENOMEM;
> > -             goto free_pdata;
> > +             return ret;
> >       }
> >
> >       /* init mcr20a local data */
> >       lp = hw->priv;
> >       lp->hw = hw;
> >       lp->spi = spi;
> > -     lp->spi->dev.platform_data = pdata;
> > -     lp->pdata = pdata;
> >
> >       /* init ieee802154_hw */
> >       hw->parent = &spi->dev;
> > @@ -1370,8 +1334,6 @@ mcr20a_probe(struct spi_device *spi)
> >
> >  free_dev:
> >       ieee802154_free_hw(lp->hw);
> > -free_pdata:
> > -     kfree(pdata);
> >
> >       return ret;
> >  }
> >
>
> The rest looks good to me and I like that we can get rid of all the
> boiler code associated with the pdata.
>
> If you could clarify (and potentially fix) the two points I raised I
> would be happy to apply this.
>
> regards
> Stefan Schmidt

regards

Xue Liu

--

Re: [PATCH 2/2] ieee802154: mcr20a: Remove struct mcr20a_platform_data

[Stefan Schmidt]

Hello Xue.

On 27/09/2018 20:38, Xue Liu wrote:
> Hi Stefan,
> On Thu, 27 Sep 2018 at 17:44, Stefan Schmidt <stefan@datenfreihafen.org> wrote:
>>
>> Hello Xue.
>>
>> On 31/08/2018 23:46, Xue Liu wrote:
>>> The struct mcr20a_platform_data is uesed only in probe function
>>> and it holds only one member. So it is not necessary to reserve it.
>>>
>>> Using gpiod family API to handle reset pin.
>>>
>>> Signed-off-by: Xue Liu <liuxuenetmail@gmail.com>
>>> ---
>>>  drivers/net/ieee802154/mcr20a.c | 64 +++++++--------------------------
>>>  1 file changed, 13 insertions(+), 51 deletions(-)
>>>
>>> diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
>>> index 04891429a554..44de81e5f140 100644
>>> --- a/drivers/net/ieee802154/mcr20a.c
>>> +++ b/drivers/net/ieee802154/mcr20a.c
>>> @@ -132,11 +132,6 @@ static const struct reg_sequence mar20a_iar_overwrites[] = {
>>>  };
>>>
>>>  #define MCR20A_VALID_CHANNELS (0x07FFF800)
>>> -
>>> -struct mcr20a_platform_data {
>>> -     int rst_gpio;
>>> -};
>>> -
>>>  #define MCR20A_MAX_BUF               (127)
>>>
>>>  #define printdev(X) (&X->spi->dev)
>>> @@ -412,7 +407,6 @@ struct mcr20a_local {
>>>       struct spi_device *spi;
>>>
>>>       struct ieee802154_hw *hw;
>>> -     struct mcr20a_platform_data *pdata;
>>>       struct regmap *regmap_dar;
>>>       struct regmap *regmap_iar;
>>>
>>> @@ -976,20 +970,6 @@ static irqreturn_t mcr20a_irq_isr(int irq, void *data)
>>>       return IRQ_HANDLED;
>>>  }
>>>
>>> -static int mcr20a_get_platform_data(struct spi_device *spi,
>>> -                                 struct mcr20a_platform_data *pdata)
>>> -{
>>> -     int ret = 0;
>>> -
>>> -     if (!spi->dev.of_node)
>>> -             return -EINVAL;
>>> -
>>> -     pdata->rst_gpio = of_get_named_gpio(spi->dev.of_node, "rst_b-gpio", 0);
>>> -     dev_dbg(&spi->dev, "rst_b-gpio: %d\n", pdata->rst_gpio);
>>> -
>>> -     return ret;
>>> -}
>>> -
>>>  static void mcr20a_hw_setup(struct mcr20a_local *lp)
>>>  {
>>>       u8 i;
>>> @@ -1249,7 +1229,7 @@ mcr20a_probe(struct spi_device *spi)
>>>  {
>>>       struct ieee802154_hw *hw;
>>>       struct mcr20a_local *lp;
>>> -     struct mcr20a_platform_data *pdata;
>>> +     struct gpio_desc *rst_b;
>>>       int irq_type;
>>>       int ret = -ENOMEM;
>>>
>>> @@ -1260,48 +1240,32 @@ mcr20a_probe(struct spi_device *spi)
>>>               return -EINVAL;
>>>       }
>>>
>>> -     pdata = kmalloc(sizeof(*pdata), GFP_KERNEL);
>>> -     if (!pdata)
>>> -             return -ENOMEM;
>>> -
>>> -     /* set mcr20a platform data */
>>> -     ret = mcr20a_get_platform_data(spi, pdata);
>>> -     if (ret < 0) {
>>> -             dev_crit(&spi->dev, "mcr20a_get_platform_data failed.\n");
>>> -             goto free_pdata;
>>> -     }
>>> -
>>> -     /* init reset gpio */
>>> -     if (gpio_is_valid(pdata->rst_gpio)) {
>>> -             ret = devm_gpio_request_one(&spi->dev, pdata->rst_gpio,
>>> -                                         GPIOF_OUT_INIT_HIGH, "reset");
>>> -             if (ret)
>>> -                     goto free_pdata;
>>> +     rst_b = devm_gpiod_get(&spi->dev, "rst_b", GPIOD_OUT_HIGH);
>>
>> I am a bit confused about the pin name here. When using
>> of_get_named_gpio() the name is "rst_b-gpio" which is the same I see
>> referenced in the devicetree bindings file.
>>
>> When switching to devm_gpiod_get() the name is shortened to "rst_b".
>> Does the gpiod API implicitly add a -gpio to the name when searching for
>> it in the dst?
>>
> Yes. The function calling tree is shown below:
> --> devm_gpiod_get()
>     --> __gpiod_get_index()
>          --> of_find_gpio()
> The definition of function of_find_gpio() is here
> https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib-of.c#L231.
> The definition of struct gpio_suffixes is here
> https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.h#L95.
> You can see that the suffix "gpio" or "gpios" is automatically added
> when it is looking for the name of gpio in the device tree.

Thanks for the explanation. The missing gpio made me wondering but this
cleared it up.

>> The reason I ask is that I would want to avoid a name change of the
>> property. That would break the dts bindings already in place.
>>
> We don't need to change the dts bindings.

Perfect, that is what I wanted to be sure about. :-)

>>> +     if (IS_ERR(rst_b)) {
>>> +             ret = PTR_ERR(rst_b);
>>> +             if (ret != -EPROBE_DEFER)
>>> +                     dev_err(&spi->dev, "Failed to get 'rst_b' gpio: %d", ret);
>>> +             return ret;
>>>       }
>>>
>>>       /* reset mcr20a */
>>> -     if (gpio_is_valid(pdata->rst_gpio)) {
>>> -             usleep_range(10, 20);
>>> -             gpio_set_value_cansleep(pdata->rst_gpio, 0);
>>> -             usleep_range(10, 20);
>>> -             gpio_set_value_cansleep(pdata->rst_gpio, 1);
>>> -             usleep_range(120, 240);
>>> -     }
>>> +     usleep_range(10, 20);
>>> +     gpiod_set_value_cansleep(rst_b, 1);
>>> +     usleep_range(10, 20);
>>> +     gpiod_set_value_cansleep(rst_b, 0);
>>> +     usleep_range(120, 240);
>>
>> With your change you reversing the setting from ->0->1 to ->1->0. Is the
>> gpiod API reverse here or did you made a copy and paste mistake? :-)
>>
> I am afraid both of assumptions are wrong here. The new GPIO
> descriptor consumer interface uses *logical* value.
> It means 0 and 1 denote GPIO deassertion and assertion. The property
> of rst_b is GPIO_ACTIVE_LOW. So the value 1
> means low in physical line and the value 0 means high.

Interesting. I got myself fooled with the very similar function names
they should work the same. Blame on me for not checking.

This patch has been applied to the wpan-next tree and will be
part of the next pull request to net-next. Thanks!

regards
Stefan Schmidt