[PATCH] drm/amd/display: Check hpd_gpio for NULL before accessing it

[Harry Wentland]

dal_gpio_open and dal_gpio_unlock_pin dereference hpd_gpio.
Check for NULL before calling those functions.

Fixes: e261568f94d6 ("drm/amd/display: add gpio lock/unlock")
Reported-by: Przemek Socha <soprwa at gmail.com>
CC: Chiawen Huang <chiawen.huang at amd.com>
CC: Tony Cheng <Tony.Cheng at amd.com>
Signed-off-by: Harry Wentland <harry.wentland at amd.com>
---

I don't have a system to test this on. Can someone give it a spin?

Harry

 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index 6d2cef05b4d7..7f5a947ad31d 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1127,10 +1127,11 @@ static bool construct(
 		link->dc->res_pool->funcs->link_init(link);
 
 	link->hpd_gpio = get_hpd_gpio(link->ctx->dc_bios, link->link_id, link->ctx->gpio_service);
-	dal_gpio_open(link->hpd_gpio, GPIO_MODE_INTERRUPT);
-	dal_gpio_unlock_pin(link->hpd_gpio);
-	if (link->hpd_gpio != NULL)
+	if (link->hpd_gpio != NULL) {
+		dal_gpio_open(link->hpd_gpio, GPIO_MODE_INTERRUPT);
+		dal_gpio_unlock_pin(link->hpd_gpio);
 		link->irq_source_hpd = dal_irq_get_source(link->hpd_gpio);
+	}
 
 	switch (link->link_id.id) {
 	case CONNECTOR_ID_HDMI_TYPE_A:
-- 
2.19.1