[PATCH 4.2 009/120] drm/amdgpu: Dont link train DisplayPort on HPD until we get the dpcd

Greg Kroah-Hartman
2015-09-19T17:39:49Z

From: Alex Deucher <alexander.deucher@amd.com>

commit a887adadb7b9ef9eb4ee48e4ad575aefcfd1db14 upstream.

This is a port of:
DRM - radeon: Don't link train DisplayPort on HPD until we get the dpcd
to amdgpu.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -75,6 +75,11 @@ void amdgpu_connector_hotplug(struct drm
if (!amdgpu_display_hpd_sense(adev, amdgpu_connector->hpd.hpd)) {
drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF);
} else if (amdgpu_atombios_dp_needs_link_train(amdgpu_connector)) {
+ /* Don't try to start link training before we
+ * have the dpcd */
+ if (!amdgpu_atombios_dp_get_dpcd(amdgpu_connector))
+ return;
+
/* set it to OFF so that drm_helper_connector_dpms()
* won't return immediately since the current state
* is ON at this point.