Hi Vinod, kernel test robot noticed the following build warnings:
https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Vinod-Govindapillai/drm-i915-display-get-rid-of-encoder-param-in-intel_audio_compute_config/20241008-163033 base: git://anongit.freedesktop.org/drm-intel for-linux-next patch link: https://lore.kernel.org/r/20241008082327.342020-7-vinod.govindapillai%40intel.com patch subject: [PATCH 6/9] drm/i915/display: iterare through channels if no feasible frequencies config: x86_64-randconfig-161-20241009 (https://download.01.org/0day-ci/archive/20241010/202410100801.8jzbrn3y-...@intel.com/config) compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff) 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 <l...@intel.com> | Reported-by: Dan Carpenter <dan.carpen...@linaro.org> | Closes: https://lore.kernel.org/r/202410100801.8jzbrn3y-...@intel.com/ smatch warnings: drivers/gpu/drm/i915/display/intel_audio.c:789 intel_audio_compute_sad() error: uninitialized symbol 'sad_freq'. vim +/sad_freq +789 drivers/gpu/drm/i915/display/intel_audio.c 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 764 static void intel_audio_compute_sad(struct drm_i915_private *i915, 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 765 int line_freq_khz, int hblank_slots_lanes, 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 766 int avail_overhead, int req_overhead, 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 767 struct cea_sad *sad) 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 768 { e2675520fb74591 Vinod Govindapillai 2024-10-08 769 u8 channels; 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 770 u8 sad_freq; 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 771 e2675520fb74591 Vinod Govindapillai 2024-10-08 772 /* e2675520fb74591 Vinod Govindapillai 2024-10-08 773 * If we don't find any supported audio frequencies for a channel, e2675520fb74591 Vinod Govindapillai 2024-10-08 774 * reduce the channel and try e2675520fb74591 Vinod Govindapillai 2024-10-08 775 */ e2675520fb74591 Vinod Govindapillai 2024-10-08 776 for (channels = sad->channels + 1; channels >= 1; channels--) { This driver is old. In the era when this driver was written, we used to just say that if you hit this bug then you deserved it. We wouldn't bother to fix something like this. These days we have syzbot doing millions of stupid things per second to try break the kernel. You'd have to use the /proc file to set sad->channels to 255. Then channels would be zero and we wouldn't enter the loop. Potentially, we could add some sanity checking to snd_hdmi_write_eld_info()? Another idea would be to make channels an int instead of a u8. My other concern is with the "+ 1". In drm_edid_cta_sad_set() we set channels as: cta_sad->channels = sad[0] & 0x07; fine. But in hdmi_update_short_audio_desc() we set channels as: a->channels = GRAB_BITS(buf, 0, 0, 3); a->channels++; The first line is exact same in both functions but in hdmi_update_short_audio_desc() we add "+ 1" and then we add another "+ 1" in this intel_audio_compute_sad() function. I suspect the a->channels++; line should be deleted. 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 777 sad_freq = intel_audio_get_pruned_audfreq(i915, line_freq_khz, 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 778 hblank_slots_lanes, 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 779 avail_overhead, e2675520fb74591 Vinod Govindapillai 2024-10-08 780 req_overhead, e2675520fb74591 Vinod Govindapillai 2024-10-08 781 channels, 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 782 sad->freq); 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 783 e2675520fb74591 Vinod Govindapillai 2024-10-08 784 /* Supported frequencies exist! No need to proceed further */ e2675520fb74591 Vinod Govindapillai 2024-10-08 785 if (sad_freq) e2675520fb74591 Vinod Govindapillai 2024-10-08 786 break; e2675520fb74591 Vinod Govindapillai 2024-10-08 787 } e2675520fb74591 Vinod Govindapillai 2024-10-08 788 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 @789 sad->freq = sad_freq; e2675520fb74591 Vinod Govindapillai 2024-10-08 790 sad->channels = channels ? channels - 1 : 0; 0f1adcd58da8c47 Vinod Govindapillai 2024-10-08 791 } -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
