[PATCH 0/3] fbdev: ssd1307fb: Make reset-gpios optional property

[PATCH 0/3] fbdev: ssd1307fb: Make reset-gpios optional property

[Jyri Sarha]

Use gpiod for reset-gpios property and make it optional. Also removes
the nerver implemented reset-active-low property from the devicetree
binding document. The default gpio binding should be enough.

Jyri Sarha (3):
  fbdev: ssd1307fb: Start to use gpiod API for reset gpio
  fbdev: ssd1307fb: Remove reset-active-low from the DT binding document
  fbdev: ssd1307fb: Make reset gpio devicetree property optional

 .../devicetree/bindings/display/ssd1307fb.txt      |  4 +--
 drivers/video/fbdev/ssd1307fb.c                    | 38 ++++++++++------------
 2 files changed, 20 insertions(+), 22 deletions(-)

-- 
1.9.1

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[PATCH 1/3] fbdev: ssd1307fb: Start to use gpiod API for reset gpio

[Jyri Sarha]

Start to use gpiod API for reset gpio.

Signed-off-by: Jyri Sarha <jsarha-l0cyMroinI0@public.gmane.org>
---
 drivers/video/fbdev/ssd1307fb.c | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index a9c45c8..b27912c 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -73,7 +73,7 @@ struct ssd1307fb_par {
 	u32 prechargep2;
 	struct pwm_device *pwm;
 	u32 pwm_period;
-	int reset;
+	struct gpio_desc *reset;
 	u32 seg_remap;
 	u32 vcomh;
 	u32 width;
@@ -562,10 +562,11 @@ static int ssd1307fb_probe(struct i2c_client *client,
 	par->device_info = (struct ssd1307fb_deviceinfo *)of_match_device(
 			ssd1307fb_of_match, &client->dev)->data;
 
-	par->reset = of_get_named_gpio(client->dev.of_node,
-					 "reset-gpios", 0);
-	if (!gpio_is_valid(par->reset)) {
-		ret = -EINVAL;
+	par->reset = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(par->reset)) {
+		dev_err(&client->dev, "failed to get reset gpio: %ld\n",
+			PTR_ERR(par->reset));
+		ret = PTR_ERR(par->reset);
 		goto fb_alloc_error;
 	}
 
@@ -643,22 +644,12 @@ static int ssd1307fb_probe(struct i2c_client *client,
 
 	fb_deferred_io_init(info);
 
-	ret = devm_gpio_request_one(&client->dev, par->reset,
-				    GPIOF_OUT_INIT_HIGH,
-				    "oled-reset");
-	if (ret) {
-		dev_err(&client->dev,
-			"failed to request gpio %d: %d\n",
-			par->reset, ret);
-		goto reset_oled_error;
-	}
-
 	i2c_set_clientdata(client, info);
 
 	/* Reset the screen */
-	gpio_set_value(par->reset, 0);
+	gpiod_set_value(par->reset, 0);
 	udelay(4);
-	gpio_set_value(par->reset, 1);
+	gpiod_set_value(par->reset, 1);
 	udelay(4);
 
 	ret = ssd1307fb_init(par);
-- 
1.9.1

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[PATCH 2/3] fbdev: ssd1307fb: Remove reset-active-low from the DT binding document

[Jyri Sarha]

Remove reset-active-low from the devicetree binding document. The actual
implementation has never been there in the driver code and there is no
reason to add it because the gpiod API supports gpio flags, including
GPIO_ACTIVE_LOW, directly trough its own devicetree binding.

Signed-off-by: Jyri Sarha <jsarha-l0cyMroinI0@public.gmane.org>
---
 Documentation/devicetree/bindings/display/ssd1307fb.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/ssd1307fb.txt b/Documentation/devicetree/bindings/display/ssd1307fb.txt
index eb31ed4..4aee67f 100644
--- a/Documentation/devicetree/bindings/display/ssd1307fb.txt
+++ b/Documentation/devicetree/bindings/display/ssd1307fb.txt
@@ -8,14 +8,14 @@ Required properties:
          0x3c or 0x3d
   - pwm: Should contain the pwm to use according to the OF device tree PWM
          specification [0]. Only required for the ssd1307.
-  - reset-gpios: Should contain the GPIO used to reset the OLED display
+  - reset-gpios: Should contain the GPIO used to reset the OLED display. See
+                 Documentation/devicetree/bindings/gpio/gpio.txt for details.
   - solomon,height: Height in pixel of the screen driven by the controller
   - solomon,width: Width in pixel of the screen driven by the controller
   - solomon,page-offset: Offset of pages (band of 8 pixels) that the screen is
     mapped to.
 
 Optional properties:
-  - reset-active-low: Is the reset gpio is active on physical low?
   - solomon,segment-no-remap: Display needs normal (non-inverted) data column
                               to segment mapping
   - solomon,com-seq: Display uses sequential COM pin configuration
-- 
1.9.1

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[PATCH 3/3] fbdev: ssd1307fb: Make reset gpio devicetree property optional

[Jyri Sarha]

Make reset gpio devicetree property optional. Depending on the board
designing there may not be a dedicated gpio for resetting the
display. Without a proper reset there may be some junk in the display
memory at probe time, so in such a case the display memory is cleared
before turning it on. The devicetree binding document is also updated.

Signed-off-by: Jyri Sarha <jsarha-l0cyMroinI0@public.gmane.org>
---
 .../devicetree/bindings/display/ssd1307fb.txt         |  4 ++--
 drivers/video/fbdev/ssd1307fb.c                       | 19 +++++++++++++------
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/ssd1307fb.txt b/Documentation/devicetree/bindings/display/ssd1307fb.txt
index 4aee67f..6617df6 100644
--- a/Documentation/devicetree/bindings/display/ssd1307fb.txt
+++ b/Documentation/devicetree/bindings/display/ssd1307fb.txt
@@ -8,14 +8,14 @@ Required properties:
          0x3c or 0x3d
   - pwm: Should contain the pwm to use according to the OF device tree PWM
          specification [0]. Only required for the ssd1307.
-  - reset-gpios: Should contain the GPIO used to reset the OLED display. See
-                 Documentation/devicetree/bindings/gpio/gpio.txt for details.
   - solomon,height: Height in pixel of the screen driven by the controller
   - solomon,width: Width in pixel of the screen driven by the controller
   - solomon,page-offset: Offset of pages (band of 8 pixels) that the screen is
     mapped to.
 
 Optional properties:
+  - reset-gpios: The GPIO used to reset the OLED display, if available. See
+                 Documentation/devicetree/bindings/gpio/gpio.txt for details.
   - solomon,segment-no-remap: Display needs normal (non-inverted) data column
                               to segment mapping
   - solomon,com-seq: Display uses sequential COM pin configuration
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index b27912c..891dfe1 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -439,6 +439,10 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
 	if (ret < 0)
 		return ret;
 
+	/* Clear the screen if we could not give reset at probe time */
+	if (!par->reset)
+		ssd1307fb_update_display(par);
+
 	/* Turn on the display */
 	ret = ssd1307fb_write_cmd(par->client, SSD1307FB_DISPLAY_ON);
 	if (ret < 0)
@@ -562,7 +566,8 @@ static int ssd1307fb_probe(struct i2c_client *client,
 	par->device_info = (struct ssd1307fb_deviceinfo *)of_match_device(
 			ssd1307fb_of_match, &client->dev)->data;
 
-	par->reset = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW);
+	par->reset = devm_gpiod_get_optional(&client->dev, "reset",
+					     GPIOD_OUT_LOW);
 	if (IS_ERR(par->reset)) {
 		dev_err(&client->dev, "failed to get reset gpio: %ld\n",
 			PTR_ERR(par->reset));
@@ -646,11 +651,13 @@ static int ssd1307fb_probe(struct i2c_client *client,
 
 	i2c_set_clientdata(client, info);
 
-	/* Reset the screen */
-	gpiod_set_value(par->reset, 0);
-	udelay(4);
-	gpiod_set_value(par->reset, 1);
-	udelay(4);
+	if (par->reset) {
+		/* Reset the screen */
+		gpiod_set_value(par->reset, 0);
+		udelay(4);
+		gpiod_set_value(par->reset, 1);
+		udelay(4);
+	}
 
 	ret = ssd1307fb_init(par);
 	if (ret)
-- 
1.9.1

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Re: [PATCH 2/3] fbdev: ssd1307fb: Remove reset-active-low from the DT binding document

[Rob Herring]

On Tue, Jun 07, 2016 at 04:51:13PM +0300, Jyri Sarha wrote:
> Remove reset-active-low from the devicetree binding document. The actual
> implementation has never been there in the driver code and there is no
> reason to add it because the gpiod API supports gpio flags, including
> GPIO_ACTIVE_LOW, directly trough its own devicetree binding.
> 
> Signed-off-by: Jyri Sarha <jsarha-l0cyMroinI0@public.gmane.org>
> ---
>  Documentation/devicetree/bindings/display/ssd1307fb.txt | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/ssd1307fb.txt b/Documentation/devicetree/bindings/display/ssd1307fb.txt
> index eb31ed4..4aee67f 100644
> --- a/Documentation/devicetree/bindings/display/ssd1307fb.txt
> +++ b/Documentation/devicetree/bindings/display/ssd1307fb.txt
> @@ -8,14 +8,14 @@ Required properties:
>           0x3c or 0x3d
>    - pwm: Should contain the pwm to use according to the OF device tree PWM
>           specification [0]. Only required for the ssd1307.
> -  - reset-gpios: Should contain the GPIO used to reset the OLED display
> +  - reset-gpios: Should contain the GPIO used to reset the OLED display. See
> +                 Documentation/devicetree/bindings/gpio/gpio.txt for details.

You should state here it is active low.

>    - solomon,height: Height in pixel of the screen driven by the controller
>    - solomon,width: Width in pixel of the screen driven by the controller
>    - solomon,page-offset: Offset of pages (band of 8 pixels) that the screen is
>      mapped to.
>  
>  Optional properties:
> -  - reset-active-low: Is the reset gpio is active on physical low?
>    - solomon,segment-no-remap: Display needs normal (non-inverted) data column
>                                to segment mapping
>    - solomon,com-seq: Display uses sequential COM pin configuration
> -- 
> 1.9.1
> 
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> To unsubscribe from this list: send the line "unsubscribe devicetree" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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