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fbdev: ssd1307fb: Make reset gpio devicetree property optional

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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.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Benoît Cousson <bcousson@baylibre.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
This commit is contained in:
Jyri Sarha 2017-02-08 16:43:59 +01:00 committed by Bartlomiej Zolnierkiewicz
parent 519b4dba58
commit fdde1a8148
2 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/devicetree/bindings/display/ssd1307fb.txt
View File

@ -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

19
drivers/video/fbdev/ssd1307fb.c
View File

@ -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)
@ -561,7 +565,8 @@ static int ssd1307fb_probe(struct i2c_client *client,
par->device_info = of_device_get_match_data(&client->dev);
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));
@ -645,11 +650,13 @@ 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)