linux-kernel - drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_factory.c:365 dc_link_construct_phy() warn: variable dereferenced before check 'link->link

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Date:   Mon, 27 Feb 2023 07:35:51 +0300
From:   Dan Carpenter <error27@...il.com>
To:     oe-kbuild@...ts.linux.dev, Wenjing Liu <wenjing.liu@....com>
Cc:     lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
        linux-kernel@...r.kernel.org,
        Alex Deucher <alexander.deucher@....com>,
        George Shen <George.Shen@....com>
Subject: drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_factory.c:365
 dc_link_construct_phy() warn: variable dereferenced before check
 'link->link_enc' (see line 362)

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   2fcd07b7ccd5fd10b2120d298363e4e6c53ccf9c
commit: 54618888d1ea7a26f8bccfb89e3c2420350c8047 drm/amd/display: break down dc_link.c
config: m68k-randconfig-m031-20230226 (https://download.01.org/0day-ci/archive/20230226/202302261837.dKavRZA5-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Reported-by: Dan Carpenter <error27@...il.com>
| Link: https://lore.kernel.org/r/202302261837.dKavRZA5-lkp@intel.com/

New smatch warnings:
drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_factory.c:365 dc_link_construct_phy() warn: variable dereferenced before check 'link->link_enc' (see line 362)
drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_dpms.c:2307 link_set_dpms_on() warn: if statement not indented

Old smatch warnings:
drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_factory.c:145 get_ddc_line() warn: inconsistent indenting
drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_factory.c:201 dc_link_construct_phy() warn: inconsistent indenting

vim +365 drivers/gpu/drm/amd/amdgpu/../display/dc/link/link_factory.c

54618888d1ea7a Wenjing Liu 2023-01-18  348  	enc_init_data.ctx = dc_ctx;
54618888d1ea7a Wenjing Liu 2023-01-18  349  	bp_funcs->get_src_obj(dc_ctx->dc_bios, link->link_id, 0,
54618888d1ea7a Wenjing Liu 2023-01-18  350  			      &enc_init_data.encoder);
54618888d1ea7a Wenjing Liu 2023-01-18  351  	enc_init_data.connector = link->link_id;
54618888d1ea7a Wenjing Liu 2023-01-18  352  	enc_init_data.channel = get_ddc_line(link);
54618888d1ea7a Wenjing Liu 2023-01-18  353  	enc_init_data.hpd_source = get_hpd_line(link);
54618888d1ea7a Wenjing Liu 2023-01-18  354  
54618888d1ea7a Wenjing Liu 2023-01-18  355  	link->hpd_src = enc_init_data.hpd_source;
54618888d1ea7a Wenjing Liu 2023-01-18  356  
54618888d1ea7a Wenjing Liu 2023-01-18  357  	enc_init_data.transmitter =
54618888d1ea7a Wenjing Liu 2023-01-18  358  		translate_encoder_to_transmitter(enc_init_data.encoder);
54618888d1ea7a Wenjing Liu 2023-01-18  359  	link->link_enc =
54618888d1ea7a Wenjing Liu 2023-01-18  360  		link->dc->res_pool->funcs->link_enc_create(dc_ctx, &enc_init_data);
54618888d1ea7a Wenjing Liu 2023-01-18  361  
54618888d1ea7a Wenjing Liu 2023-01-18 @362  	DC_LOG_DC("BIOS object table - DP_IS_USB_C: %d", link->link_enc->features.flags.bits.DP_IS_USB_C);
                                                                                                 ^^^^^^^^^^^^^^^^

54618888d1ea7a Wenjing Liu 2023-01-18  363  	DC_LOG_DC("BIOS object table - IS_DP2_CAPABLE: %d", link->link_enc->features.flags.bits.IS_DP2_CAPABLE);
                                                                                                    ^^^^^^^^^^^^^^^^

54618888d1ea7a Wenjing Liu 2023-01-18  364  
54618888d1ea7a Wenjing Liu 2023-01-18 @365  	if (!link->link_enc) {
                                                     ^^^^^^^^^^^^^^
Too late.

54618888d1ea7a Wenjing Liu 2023-01-18  366  		DC_ERROR("Failed to create link encoder!\n");
54618888d1ea7a Wenjing Liu 2023-01-18  367  		goto link_enc_create_fail;
54618888d1ea7a Wenjing Liu 2023-01-18  368  	}
54618888d1ea7a Wenjing Liu 2023-01-18  369  
54618888d1ea7a Wenjing Liu 2023-01-18  370  	/* Update link encoder tracking variables. These are used for the dynamic
54618888d1ea7a Wenjing Liu 2023-01-18  371  	 * assignment of link encoders to streams.
54618888d1ea7a Wenjing Liu 2023-01-18  372  	 */
54618888d1ea7a Wenjing Liu 2023-01-18  373  	link->eng_id = link->link_enc->preferred_engine;
54618888d1ea7a Wenjing Liu 2023-01-18  374  	link->dc->res_pool->link_encoders[link->eng_id - ENGINE_ID_DIGA] = link->link_enc;
54618888d1ea7a Wenjing Liu 2023-01-18  375  	link->dc->res_pool->dig_link_enc_count++;
54618888d1ea7a Wenjing Liu 2023-01-18  376  
54618888d1ea7a Wenjing Liu 2023-01-18  377  	link->link_enc_hw_inst = link->link_enc->transmitter;

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests