[PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas <javierm@redhat.com>]

Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
so lets relax this in the driver and make the reset GPIO to be optional.

The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
returns NULL when there isn't a reset-gpios property defined in a DT node.

The DT binding schema for "sitronix,st7571" that require a reset GPIO will
enforce the "reset-gpios" to be present, due being a required DT property.
But in the driver itself the property can be made optional if not defined.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

 drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
index eec846892962..73e8db25f895 100644
--- a/drivers/gpu/drm/sitronix/st7571-i2c.c
+++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
@@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
 	st7571->nlines = dt.vactive.typ;
 	st7571->ncols = dt.hactive.typ;
 
-	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(st7571->reset))
-		return PTR_ERR(st7571->reset);
+		return dev_err_probe(dev, PTR_ERR(st7571->reset),
+				     "Failed to get reset gpio\n");
 
 	return 0;
 }
 
 static void st7571_reset(struct st7571_device *st7571)
 {
+	if (!st7571->reset)
+		return;
+
 	gpiod_set_value_cansleep(st7571->reset, 1);
 	fsleep(20);
 	gpiod_set_value_cansleep(st7571->reset, 0);
-- 
2.49.0