Hi Tejas, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on drm-tip/drm-tip] [cannot apply to drm-intel/for-linux-next v5.17-rc8 next-20220316] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Tejas-Upadhyay/drm-i915-gt-preempt-engine-to-idle-before-reset/20220316-215054 base: git://anongit.freedesktop.org/drm/drm-tip drm-tip config: x86_64-randconfig-a005 (https://download.01.org/0day-ci/archive/20220317/202203170430.cDmFRpYE-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project a6ec1e3d798f8eab43fb3a91028c6ab04e115fcb) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/06139e9768f3f8e43bf061ae6292feb7daf07944 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Tejas-Upadhyay/drm-i915-gt-preempt-engine-to-idle-before-reset/20220316-215054 git checkout 06139e9768f3f8e43bf061ae6292feb7daf07944 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/gpu/drm/i915/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): >> drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2524:7: warning: variable 'err' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] if (READ_ONCE(el->pending[0])) { ^~~~~~~~~~~~~~~~~~~~~~~~~ include/asm-generic/rwonce.h:47:28: note: expanded from macro 'READ_ONCE' #define READ_ONCE(x) \ ^ drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2538:9: note: uninitialized use occurs here return err; ^~~ drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2524:3: note: remove the 'if' if its condition is always true if (READ_ONCE(el->pending[0])) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2489:6: warning: variable 'err' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] if (*el->active) { /* preempt to idle required */ ^~~~~~~~~~~ drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2538:9: note: uninitialized use occurs here return err; ^~~ drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2489:2: note: remove the 'if' if its condition is always true if (*el->active) { /* preempt to idle required */ ^~~~~~~~~~~~~~~~~ drivers/gpu/drm/i915/gt/intel_execlists_submission.c:2462:9: note: initialize the variable 'err' to silence this warning int err; ^ = 0 2 warnings generated. vim +2524 drivers/gpu/drm/i915/gt/intel_execlists_submission.c c3b2b6ffcd31318 Chris Wilson 2022-03-16 2453 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2454 /* XXX return error and force a full reset if we fail to c3b2b6ffcd31318 Chris Wilson 2022-03-16 2455 * preempt-to-idle c3b2b6ffcd31318 Chris Wilson 2022-03-16 2456 */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2457 static int execlists_suspend(struct intel_engine_cs *engine) c3b2b6ffcd31318 Chris Wilson 2022-03-16 2458 { c3b2b6ffcd31318 Chris Wilson 2022-03-16 2459 struct i915_sched_engine *se = engine->sched_engine; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2460 struct intel_engine_execlists * const el = &engine->execlists; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2461 unsigned long timeout; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2462 int err; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2463 06139e9768f3f8e Tejas Upadhyay 2022-03-16 2464 if (!intel_engine_pm_get_if_awake(engine)) 06139e9768f3f8e Tejas Upadhyay 2022-03-16 2465 return 0; 06139e9768f3f8e Tejas Upadhyay 2022-03-16 2466 ENGINE_TRACE(engine, "supending active engine\n"); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2467 /* Stop further submissions, but listen for our own preempt-to-idle */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2468 tasklet_disable(&se->tasklet); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2469 se->tasklet.callback = suspend_tasklet; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2470 tasklet_enable(&se->tasklet); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2471 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2472 /* c3b2b6ffcd31318 Chris Wilson 2022-03-16 2473 * We have to wait for the HW to complete a pending context switch c3b2b6ffcd31318 Chris Wilson 2022-03-16 2474 * before we can write to ELS[PQ] again. Otherwise the behaviour c3b2b6ffcd31318 Chris Wilson 2022-03-16 2475 * is undefined... c3b2b6ffcd31318 Chris Wilson 2022-03-16 2476 * c3b2b6ffcd31318 Chris Wilson 2022-03-16 2477 * If the engine is truly hung, it will neither clear pending c3b2b6ffcd31318 Chris Wilson 2022-03-16 2478 * nor respond to our preemption request. In the later case, c3b2b6ffcd31318 Chris Wilson 2022-03-16 2479 * we have the dilemma of how to restore hang detection... c3b2b6ffcd31318 Chris Wilson 2022-03-16 2480 */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2481 timeout = jiffies + HZ / 2; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2482 while (READ_ONCE(el->pending[0]) && time_before(jiffies, timeout)) c3b2b6ffcd31318 Chris Wilson 2022-03-16 2483 intel_engine_flush_submission(engine); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2484 if (READ_ONCE(el->pending[0])) { c3b2b6ffcd31318 Chris Wilson 2022-03-16 2485 err = -EBUSY; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2486 goto err; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2487 } c3b2b6ffcd31318 Chris Wilson 2022-03-16 2488 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2489 if (*el->active) { /* preempt to idle required */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2490 struct i915_request **pending = el->pending; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2491 struct intel_context *ce = el->preempt_context; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2492 u64 desc; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2493 int n; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2494 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2495 /* Always submit an empty / idle context */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2496 desc = lrc_update_regs(ce, engine, ce->ring->tail); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2497 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2498 /* c3b2b6ffcd31318 Chris Wilson 2022-03-16 2499 * As we submit a dummy context, we will get two events. c3b2b6ffcd31318 Chris Wilson 2022-03-16 2500 * First a preemption of the running context, causing us c3b2b6ffcd31318 Chris Wilson 2022-03-16 2501 * to promote el->pending to el->inflight. And then c3b2b6ffcd31318 Chris Wilson 2022-03-16 2502 * we will receive a completion event as our context c3b2b6ffcd31318 Chris Wilson 2022-03-16 2503 * idles. c3b2b6ffcd31318 Chris Wilson 2022-03-16 2504 * c3b2b6ffcd31318 Chris Wilson 2022-03-16 2505 * We can use any dummy request here for tracking the c3b2b6ffcd31318 Chris Wilson 2022-03-16 2506 * preemption events. c3b2b6ffcd31318 Chris Wilson 2022-03-16 2507 */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2508 execlists_schedule_in(*el->active, 0); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2509 *pending++ = i915_request_get(*el->active); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2510 *pending++ = NULL; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2511 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2512 /* Tell the HW to preempt to our special context */ c3b2b6ffcd31318 Chris Wilson 2022-03-16 2513 for (n = execlists_num_ports(el); --n; ) c3b2b6ffcd31318 Chris Wilson 2022-03-16 2514 write_desc(el, 0, n); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2515 write_desc(el, desc, 0); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2516 if (el->ctrl_reg) c3b2b6ffcd31318 Chris Wilson 2022-03-16 2517 writel(EL_CTRL_LOAD, el->ctrl_reg); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2518 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2519 timeout = jiffies + HZ / 2; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2520 while (READ_ONCE(el->pending[0]) && c3b2b6ffcd31318 Chris Wilson 2022-03-16 2521 time_before(jiffies, timeout)) c3b2b6ffcd31318 Chris Wilson 2022-03-16 2522 intel_engine_flush_submission(engine); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2523 c3b2b6ffcd31318 Chris Wilson 2022-03-16 @2524 if (READ_ONCE(el->pending[0])) { c3b2b6ffcd31318 Chris Wilson 2022-03-16 2525 err = -EIO; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2526 goto err; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2527 } c3b2b6ffcd31318 Chris Wilson 2022-03-16 2528 } c3b2b6ffcd31318 Chris Wilson 2022-03-16 2529 06139e9768f3f8e Tejas Upadhyay 2022-03-16 2530 goto out; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2531 c3b2b6ffcd31318 Chris Wilson 2022-03-16 2532 err: c3b2b6ffcd31318 Chris Wilson 2022-03-16 2533 tasklet_disable(&se->tasklet); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2534 se->tasklet.callback = execlists_submission_tasklet; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2535 tasklet_enable(&se->tasklet); 06139e9768f3f8e Tejas Upadhyay 2022-03-16 2536 out: 06139e9768f3f8e Tejas Upadhyay 2022-03-16 2537 intel_engine_pm_put(engine); c3b2b6ffcd31318 Chris Wilson 2022-03-16 2538 return err; c3b2b6ffcd31318 Chris Wilson 2022-03-16 2539 } c3b2b6ffcd31318 Chris Wilson 2022-03-16 2540 --- 0-DAY CI Kernel Test Service https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
