[Intel-gfx] still experiencing oops connecting Laptop to docking Station

[Daniel Vetter]

On Thu, May 21, 2015 at 12:32:18PM +0200, Nicolas Kalkhof wrote:
> > This only contains the pile of WARNINGs and not the Oops itself. I guess
> > we still need a picture (and you need to change the system console logging
> > to make sure the debug stuff shows up to). At least at the bottom of your
> > past there's from drm or i915, indicating that the crucial debug info
> > didn't make it out before the machine died.
> 
> Ok, I've set CONFIG_MESSAGE_LOGLEVEL_DEFAULT=7 to squeeze some more debug info out of the kernel. For the OOPS I still have to take a picture since kdump seems to be broken for me.
> 
> http://pastebin.com/9mxRgNa2
> 
> > I just want the decoded address (which I read from the oops, if you
> > recompile the kernel it might have changed so please double check). I.e.
> > the above two lines is all the howto you need. But please use "list"
> > instead of "break" as Chris suggested.
> 
> Gotcha!
> 
> gdb) list *drm_atomic_helper_check_modeset+0x2c5
> 0x955 is in drm_atomic_helper_check_modeset (drivers/gpu/drm/drm_atomic_helper.c:235).
> 230             }
> 231
> 232             connector_state->best_encoder = new_encoder;
> 233             idx = drm_crtc_index(connector_state->crtc);
> 234
> 235             crtc_state = state->crtc_states[idx];
> 236             crtc_state->mode_changed = true;
> 237
> 238             DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d]\n",
> 239                              connector->base.id,
> (gdb)
> 
> Address drm_atomic_helper_check_modeset+0x2c5/0x990 is the first line in the call trace.
> One more thing: When I fire up X BEFORE I connect to the docking there are no OOPSES and I can switch between DP/eDP. As soon as I kill X however my machine dies.

Ah, Chris hunch against my claim that this is impossible was spot-on. Can
you please try the below hack please and grab dmesg? Hopefully the kernel
won't die any more at least.
-Daniel
---
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index b82ef6262469..15ba72fb98dd 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -157,6 +157,7 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
 	struct drm_connector *connector;
 	struct drm_connector_state *connector_state;
 	struct drm_crtc_state *crtc_state;
+	struct drm_crtc *saved_crtc;
 	int idx, ret;
 
 	connector = state->connectors[conn_idx];
@@ -195,6 +196,8 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
 		return 0;
 	}
 
+	saved_crtc = connector_state->crtc;
+
 	funcs = connector->helper_private;
 	new_encoder = funcs->best_encoder(connector);
 
@@ -230,7 +233,8 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
 	}
 
 	connector_state->best_encoder = new_encoder;
-	idx = drm_crtc_index(connector_state->crtc);
+	WARN_ON(!connector_state->crtc);
+	idx = drm_crtc_index(saved_crtc);
 
 	crtc_state = state->crtc_states[idx];
 	crtc_state->mode_changed = true;
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch