Op 13-07-15 om 08:22 schreef Daniel Vetter:
On Sun, Jul 12, 2015 at 09:52:51AM -0700, Linus Torvalds wrote:
On Sun, Jul 12, 2015 at 1:03 AM, Jörg Otte jrg.otte@gmail.com wrote:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000009 IP: [<ffffffffbd3447bb>] 0xffffffffbd3447bb
Ugh. Please enable KALLSYMS to get sane symbols.
But yes, "crtc_state->base.active" is at offset 9 from "crtc_state", so it's pretty clearly just that change frm
if (intel_crtc->active) {
if (crtc_state->base.active) {and "crtc_state" is NULL.
And the code very much knows that crtc_state can be NULL, since it's initialized with
crtc_state = state->base.state ? intel_atomic_get_crtc_state(state->base.state,intel_crtc) : NULL;
Tssk. Daniel? Should I just revert that commit dec4f799d0a4 ("drm/i915: Use crtc_state->active in primary check_plane func") for now, or is there a better fix? Like just checking crtc_state for NULL?
Indeed embarrassing. I've missed that we still have 1 caller left that's using the transitional helpers, and those don't fill out plane_state->state backpointers to the global atomic update since there is no global atomic update for transitional helpers. Below diff should fix this - we need to preferentially check crts_state->active and if that's not set intel_crtc->active should yield the right result for the one remaining caller (it's in the crtc_disable paths).
For cheap excuses why i915 is so crap in 4.2: Thanks to a hipshot decision to transition to a different QA team ("we'll do this in 1 week without upfront planing") I essentially don't have proper QA support for 1-2 months by now. The other trouble in this area specifically is that this code is already completely changed in -next again, so any testing done on integration trees (like -next or drm-intel-nightly) won't test any patches for 4.2. -Daniel
Oh and Signed-off-by: Daniel Vetter daniel.vetter@intel.com in case you decide to apply this right away.
Well your version has the benefit of compiling without errors. :-)
Reviewed-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com