[linux-next:master 910/1340] drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:857 amdgpu_acpi_init() warn: this array is probably non-NULL. 'dm->backlight_dev'

[linux-next:master 910/1340] drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:857 amdgpu_acpi_init() warn: this array is probably non-NULL. 'dm->backlight_dev'

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: Alex Deucher <alexander.deucher@amd.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   8f0df15bafc1e1c92b6d96bf8ef24dd8be3aec7b
commit: 6728748313351e2ce2f07c929f1328730379d765 [910/1340] drm/amdgpu/display: add support for multiple backlights
:::::: branch date: 8 hours ago
:::::: commit date: 5 days ago
config: x86_64-randconfig-m001-20210713 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

New smatch warnings:
drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:857 amdgpu_acpi_init() warn: this array is probably non-NULL. 'dm->backlight_dev'
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:3552 amdgpu_dm_backlight_update_status() error: testing array offset 'i' after use.
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:3594 amdgpu_dm_backlight_get_brightness() error: testing array offset 'i' after use.

Old smatch warnings:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:1336 amdgpu_dm_fini() error: we previously assumed 'adev->dm.dc' could be null (see line 1324)
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:1349 amdgpu_dm_fini() warn: variable dereferenced before check 'adev->dm.dc' (see line 1336)
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:5888 create_stream_for_sink() error: we previously assumed 'aconnector->dc_sink' could be null (see line 5786)
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:8192 handle_cursor_update() error: we previously assumed 'afb' could be null (see line 8151)

vim +857 drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c

d38ceaf99ed015 Alex Deucher 2015-04-20  837  
d38ceaf99ed015 Alex Deucher 2015-04-20  838  /* Call all ACPI methods here */
d38ceaf99ed015 Alex Deucher 2015-04-20  839  /**
d38ceaf99ed015 Alex Deucher 2015-04-20  840   * amdgpu_acpi_init - init driver acpi support
d38ceaf99ed015 Alex Deucher 2015-04-20  841   *
d38ceaf99ed015 Alex Deucher 2015-04-20  842   * @adev: amdgpu_device pointer
d38ceaf99ed015 Alex Deucher 2015-04-20  843   *
d38ceaf99ed015 Alex Deucher 2015-04-20  844   * Verifies the AMD ACPI interfaces and registers with the acpi
d38ceaf99ed015 Alex Deucher 2015-04-20  845   * notifier chain (all asics).
d38ceaf99ed015 Alex Deucher 2015-04-20  846   * Returns 0 on success, error on failure.
d38ceaf99ed015 Alex Deucher 2015-04-20  847   */
d38ceaf99ed015 Alex Deucher 2015-04-20  848  int amdgpu_acpi_init(struct amdgpu_device *adev)
d38ceaf99ed015 Alex Deucher 2015-04-20  849  {
f9b7f3703ff977 Alex Deucher 2021-05-25  850  	struct amdgpu_atif *atif = &amdgpu_acpi_priv.atif;
d38ceaf99ed015 Alex Deucher 2015-04-20  851  
97d798b276e94a Alex Deucher 2020-05-05  852  #if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) || defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)
9c27bc97aff8bb Ye Bin       2020-10-09  853  	if (atif->notifications.brightness_change) {
97d798b276e94a Alex Deucher 2020-05-05  854  		if (amdgpu_device_has_dc_support(adev)) {
97d798b276e94a Alex Deucher 2020-05-05  855  #if defined(CONFIG_DRM_AMD_DC)
97d798b276e94a Alex Deucher 2020-05-05  856  			struct amdgpu_display_manager *dm = &adev->dm;
77bf762f8b3011 Alex Deucher 2021-05-19 @857  			if (dm->backlight_dev)
6728748313351e Alex Deucher 2021-07-08  858  				atif->bd = dm->backlight_dev[0];
97d798b276e94a Alex Deucher 2020-05-05  859  #endif
97d798b276e94a Alex Deucher 2020-05-05  860  		} else {
d38ceaf99ed015 Alex Deucher 2015-04-20  861  			struct drm_encoder *tmp;
d38ceaf99ed015 Alex Deucher 2015-04-20  862  
d38ceaf99ed015 Alex Deucher 2015-04-20  863  			/* Find the encoder controlling the brightness */
4a580877bdcb83 Luben Tuikov 2020-08-24  864  			list_for_each_entry(tmp, &adev_to_drm(adev)->mode_config.encoder_list,
d38ceaf99ed015 Alex Deucher 2015-04-20  865  					    head) {
d38ceaf99ed015 Alex Deucher 2015-04-20  866  				struct amdgpu_encoder *enc = to_amdgpu_encoder(tmp);
d38ceaf99ed015 Alex Deucher 2015-04-20  867  
d38ceaf99ed015 Alex Deucher 2015-04-20  868  				if ((enc->devices & (ATOM_DEVICE_LCD_SUPPORT)) &&
d38ceaf99ed015 Alex Deucher 2015-04-20  869  				    enc->enc_priv) {
d38ceaf99ed015 Alex Deucher 2015-04-20  870  					struct amdgpu_encoder_atom_dig *dig = enc->enc_priv;
d38ceaf99ed015 Alex Deucher 2015-04-20  871  					if (dig->bl_dev) {
97d798b276e94a Alex Deucher 2020-05-05  872  						atif->bd = dig->bl_dev;
d38ceaf99ed015 Alex Deucher 2015-04-20  873  						break;
d38ceaf99ed015 Alex Deucher 2015-04-20  874  					}
d38ceaf99ed015 Alex Deucher 2015-04-20  875  				}
d38ceaf99ed015 Alex Deucher 2015-04-20  876  			}
d38ceaf99ed015 Alex Deucher 2015-04-20  877  		}
97d798b276e94a Alex Deucher 2020-05-05  878  	}
97d798b276e94a Alex Deucher 2020-05-05  879  #endif
f9b7f3703ff977 Alex Deucher 2021-05-25  880  	adev->acpi_nb.notifier_call = amdgpu_acpi_event;
f9b7f3703ff977 Alex Deucher 2021-05-25  881  	register_acpi_notifier(&adev->acpi_nb);
f9b7f3703ff977 Alex Deucher 2021-05-25  882  
f9b7f3703ff977 Alex Deucher 2021-05-25  883  	return 0;
f9b7f3703ff977 Alex Deucher 2021-05-25  884  }
f9b7f3703ff977 Alex Deucher 2021-05-25  885  

:::::: The code at line 857 was first introduced by commit
:::::: 77bf762f8b3011b2d00eb49098071952956da892 drm/amdgpu/acpi: unify ATCS handling (v3)

:::::: TO: Alex Deucher <alexander.deucher@amd.com>
:::::: CC: Alex Deucher <alexander.deucher@amd.com>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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