[PATCH v3 2/2] drm/tiny: panel-mipi-dbi: Allow sharing the D/C GPIO

[Otto Pflüger]

Displays that are connected to the same SPI bus may share the D/C GPIO.
Use GPIOD_FLAGS_BIT_NONEXCLUSIVE to allow access to the same GPIO for
multiple panel-mipi-dbi instances. Exclusive access to the GPIO during
transfers is ensured by the locking in drm_mipi_dbi.c.

Signed-off-by: Otto Pflüger <otto.pflueger at abscue.de>
---
 drivers/gpu/drm/tiny/panel-mipi-dbi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tiny/panel-mipi-dbi.c b/drivers/gpu/drm/tiny/panel-mipi-dbi.c
index eb9f13f18a02..f80a141fcf36 100644
--- a/drivers/gpu/drm/tiny/panel-mipi-dbi.c
+++ b/drivers/gpu/drm/tiny/panel-mipi-dbi.c
@@ -307,7 +307,8 @@ static int panel_mipi_dbi_spi_probe(struct spi_device *spi)
 	if (IS_ERR(dbi->reset))
 		return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get GPIO 'reset'\n");
 
-	dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW);
+	/* Multiple panels can share the "dc" GPIO, but only if they are on the same SPI bus! */
+	dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
 	if (IS_ERR(dc))
 		return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 'dc'\n");
 
-- 
2.39.1