[PATCH v3 6/6] drm/rockchip: Check return value of cdn_dp_grf_write() in error path

[Jiaqi]

In cdn_dp_enable_phy(), when an error occurs after the GRF register has
been set to DPTX_HPD_SEL, the cleanup path at err_phy calls
cdn_dp_grf_write() to restore DPTX_HPD_DEL, but the return value is
ignored.

If this restore write fails (e.g., due to a bus timeout or GRF power
loss), the GRF register remains in the DPTX_HPD_SEL state. This leaves
the DP PHY control in an inconsistent state, which can cause subsequent
DP link initialization to fail or produce undefined behavior.

Fix by checking the return value of cdn_dp_grf_write() in the error
path and logging an error if it fails.

Signed-off-by: Jiaqi <shijiaqi_develop at 163.com>
---
 drivers/gpu/drm/rockchip/cdn-dp-core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/cdn-dp-core.c b/drivers/gpu/drm/rockchip/cdn-dp-core.c
index 8afabe2118a9..1234567890ab 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-core.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-core.c
@@ -425,8 +425,9 @@ err_power_on:
 		port->phy_enabled = false;

 err_phy:
-	cdn_dp_grf_write(dp, GRF_SOC_CON26,
-			 DPTX_HPD_SEL_MASK | DPTX_HPD_DEL);
+	ret = cdn_dp_grf_write(dp, GRF_SOC_CON26,
+			       DPTX_HPD_SEL_MASK | DPTX_HPD_DEL);
+	if (ret)
+		DRM_DEV_ERROR(dp->dev, "Failed to restore HPD_DEL: %d\n", ret);
 	return ret;
 }

--
2.40.0