The "grf" clock is optional for Rockchip eDP controller(RK3399 needs
while RK3288 and RK3588 do not).

It can make the code more concise to use devm_clk_get_optional()
instead of devm_clk_get() with extra checks.

In addtion, DRM_DEV_ERROR() is replaced by dev_err_probe().

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

------

Changes in v2:
- Replace DRM_DEV_ERROR() with dev_err_probe().

Changes in v3:
- Update Reviewed-by tag.
- Fix the spelling error 'consice' to 'concise'.
---
 drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
index d30f0983a53a..937f83cf42fc 100644
--- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
@@ -335,15 +335,9 @@ static int rockchip_dp_of_probe(struct rockchip_dp_device *dp)
 		return PTR_ERR(dp->grf);
 	}
 
-	dp->grfclk = devm_clk_get(dev, "grf");
-	if (PTR_ERR(dp->grfclk) == -ENOENT) {
-		dp->grfclk = NULL;
-	} else if (PTR_ERR(dp->grfclk) == -EPROBE_DEFER) {
-		return -EPROBE_DEFER;
-	} else if (IS_ERR(dp->grfclk)) {
-		DRM_DEV_ERROR(dev, "failed to get grf clock\n");
-		return PTR_ERR(dp->grfclk);
-	}
+	dp->grfclk = devm_clk_get_optional(dev, "grf");
+	if (IS_ERR(dp->grfclk))
+		return dev_err_probe(dev, PTR_ERR(dp->grfclk), "failed to get grf clock\n");
 
 	dp->pclk = devm_clk_get(dev, "pclk");
 	if (IS_ERR(dp->pclk)) {
-- 
2.34.1