Re: [Intel-gfx] [PATCH 1/2] drm/display/dp: Default 8 bpc support when DSC is supported

[kernel test robot <lkp@intel.com>]

Hi Ankit,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-tip/drm-tip]
[also build test WARNING on linus/master v6.5-rc7 next-20230823]
[cannot apply to drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-misc/drm-misc-next]
[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/Ankit-Nautiyal/drm-display-dp-Default-8-bpc-support-when-DSC-is-supported/20230823-195946
base:   git://anongit.freedesktop.org/drm/drm-tip drm-tip
patch link:    https://lore.kernel.org/r/20230823115425.715644-2-ankit.k.nautiyal%40intel.com
patch subject: [PATCH 1/2] drm/display/dp: Default 8 bpc support when DSC is supported
config: i386-randconfig-r036-20230823 (https://download.01.org/0day-ci/archive/20230824/202308240007.1edS9XsL-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce: (https://download.01.org/0day-ci/archive/20230824/202308240007.1edS9XsL-lkp@intel.com/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 <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308240007.1edS9XsL-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/display/drm_dp_helper.c:2451:6: warning: logical not is only applied to the left hand side of this bitwise operator [-Wlogical-not-parentheses]
           if (!dsc_dpcd[DP_DSC_SUPPORT] & DP_DSC_DECOMPRESSION_IS_SUPPORTED)
               ^                         ~
   drivers/gpu/drm/display/drm_dp_helper.c:2451:6: note: add parentheses after the '!' to evaluate the bitwise operator first
           if (!dsc_dpcd[DP_DSC_SUPPORT] & DP_DSC_DECOMPRESSION_IS_SUPPORTED)
               ^
                (                                                           )
   drivers/gpu/drm/display/drm_dp_helper.c:2451:6: note: add parentheses around left hand side expression to silence this warning
           if (!dsc_dpcd[DP_DSC_SUPPORT] & DP_DSC_DECOMPRESSION_IS_SUPPORTED)
               ^
               (                        )
   1 warning generated.


vim +2451 drivers/gpu/drm/display/drm_dp_helper.c

  2428	
  2429	/**
  2430	 * drm_dp_dsc_sink_supported_input_bpcs() - Get all the input bits per component
  2431	 * values supported by the DSC sink.
  2432	 * @dsc_dpcd: DSC capabilities from DPCD
  2433	 * @dsc_bpc: An array to be filled by this helper with supported
  2434	 *           input bpcs.
  2435	 *
  2436	 * Read the DSC DPCD from the sink device to parse the supported bits per
  2437	 * component values. This is used to populate the DSC parameters
  2438	 * in the &struct drm_dsc_config by the driver.
  2439	 * Driver creates an infoframe using these parameters to populate
  2440	 * &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
  2441	 * infoframe using the helper function drm_dsc_pps_infoframe_pack()
  2442	 *
  2443	 * Returns:
  2444	 * Number of input BPC values parsed from the DPCD
  2445	 */
  2446	int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
  2447						 u8 dsc_bpc[3])
  2448	{
  2449		int num_bpc = 0;
  2450	
> 2451		if (!dsc_dpcd[DP_DSC_SUPPORT] & DP_DSC_DECOMPRESSION_IS_SUPPORTED)
  2452			return 0;
  2453	
  2454		u8 color_depth = dsc_dpcd[DP_DSC_DEC_COLOR_DEPTH_CAP - DP_DSC_SUPPORT];
  2455	
  2456		if (color_depth & DP_DSC_12_BPC)
  2457			dsc_bpc[num_bpc++] = 12;
  2458		if (color_depth & DP_DSC_10_BPC)
  2459			dsc_bpc[num_bpc++] = 10;
  2460	
  2461		/* A DP DSC Sink devices shall support 8 bpc. */
  2462		dsc_bpc[num_bpc++] = 8;
  2463	
  2464		return num_bpc;
  2465	}
  2466	EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs);
  2467	

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