Re: [PATCH v9.6] drm/i915: Disable "busy" pmu event on CONFIG_PREEMPT_RT

Hi Maarten,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-i915/for-linux-next]
[also build test WARNING on drm-i915/for-linux-next-fixes drm-tip/drm-tip drm/drm-next drm-misc/drm-misc-next daeinki-drm-exynos/exynos-drm-next linus/master v7.2-rc5 next-20260731]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Maarten-Lankhorst/drm-i915-Disable-busy-pmu-event-on-CONFIG_PREEMPT_RT/20260731-223850
base:   https://gitlab.freedesktop.org/drm/i915/kernel.git for-linux-next
patch link:    https://lore.kernel.org/r/20260623132734.227322-1-dev%40lankhorst.se
patch subject: [PATCH v9.6] drm/i915: Disable "busy" pmu event on CONFIG_PREEMPT_RT
config: i386-randconfig-141-20260801 (https://download.01.org/0day-ci/archive/20260801/[email protected]/config)
compiler: clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
smatch: v0.5.0-9187-g5189e3fb
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260801/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/i915/i915_pmu.c:560:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
     560 |         case I915_SAMPLE_WAIT:
         |         ^
   drivers/gpu/drm/i915/i915_pmu.c:560:2: note: insert 'break;' to avoid fall-through
     560 |         case I915_SAMPLE_WAIT:
         |         ^
         |         break; 
   1 warning generated.


vim +560 drivers/gpu/drm/i915/i915_pmu.c

b46a33e271ed81b Tvrtko Ursulin    2017-11-21  550  
109ec558370f781 Tvrtko Ursulin    2018-01-11  551  static int
109ec558370f781 Tvrtko Ursulin    2018-01-11  552  engine_event_status(struct intel_engine_cs *engine,
109ec558370f781 Tvrtko Ursulin    2018-01-11  553  		    enum drm_i915_pmu_engine_sample sample)
b46a33e271ed81b Tvrtko Ursulin    2017-11-21  554  {
109ec558370f781 Tvrtko Ursulin    2018-01-11  555  	switch (sample) {
b46a33e271ed81b Tvrtko Ursulin    2017-11-21  556  	case I915_SAMPLE_BUSY:
ae7243df39c4099 Maarten Lankhorst 2026-06-23  557  		/* The guc submission engine->busyness() callback has issues with CONFIG_PREEMPT_RT */
ae7243df39c4099 Maarten Lankhorst 2026-06-23  558  		if (IS_ENABLED(CONFIG_PREEMPT_RT) && intel_uc_uses_guc_submission(&engine->gt->uc))
ae7243df39c4099 Maarten Lankhorst 2026-06-23  559  			return -ENODEV;
b46a33e271ed81b Tvrtko Ursulin    2017-11-21 @560  	case I915_SAMPLE_WAIT:
b46a33e271ed81b Tvrtko Ursulin    2017-11-21  561  		break;
b46a33e271ed81b Tvrtko Ursulin    2017-11-21  562  	case I915_SAMPLE_SEMA:
651e7d48577ae28 Lucas De Marchi   2021-06-05  563  		if (GRAPHICS_VER(engine->i915) < 6)
109ec558370f781 Tvrtko Ursulin    2018-01-11  564  			return -ENODEV;
109ec558370f781 Tvrtko Ursulin    2018-01-11  565  		break;
109ec558370f781 Tvrtko Ursulin    2018-01-11  566  	default:
109ec558370f781 Tvrtko Ursulin    2018-01-11  567  		return -ENOENT;
109ec558370f781 Tvrtko Ursulin    2018-01-11  568  	}
109ec558370f781 Tvrtko Ursulin    2018-01-11  569  
109ec558370f781 Tvrtko Ursulin    2018-01-11  570  	return 0;
109ec558370f781 Tvrtko Ursulin    2018-01-11  571  }
109ec558370f781 Tvrtko Ursulin    2018-01-11  572  

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