[Patch v3 2/2] drm/dp_mst: Add helper to get port number at specific LCT from RAD

[kernel test robot]

Hi Wayne,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm/drm-next]
[also build test WARNING on drm-exynos/exynos-drm-next linus/master drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-misc/drm-misc-next drm-tip/drm-tip v6.13-rc6 next-20250110]
[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/Wayne-Lin/drm-dp_mst-Fix-drm-RAD-print/20250110-103837
base:   git://anongit.freedesktop.org/drm/drm drm-next
patch link:    https://lore.kernel.org/r/20250110023618.66401-3-Wayne.Lin%40amd.com
patch subject: [Patch v3 2/2] drm/dp_mst: Add helper to get port number at specific LCT from RAD
config: csky-randconfig-002-20250111 (https://download.01.org/0day-ci/archive/20250111/202501111402.k6z2xVCI-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250111/202501111402.k6z2xVCI-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 at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202501111402.k6z2xVCI-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/display/drm_dp_mst_topology.c: In function 'drm_dp_mst_rad_to_str':
>> drivers/gpu/drm/display/drm_dp_mst_topology.c:201:81: warning: passing argument 2 of 'drm_dp_mst_get_ufp_num_at_lct_from_rad' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     201 |                 unpacked_rad[i] = drm_dp_mst_get_ufp_num_at_lct_from_rad(i + 1, rad);
         |                                                                                 ^~~
   drivers/gpu/drm/display/drm_dp_mst_topology.c:179:52: note: expected 'u8 *' {aka 'unsigned char *'} but argument is of type 'const u8 *' {aka 'const unsigned char *'}
     179 | drm_dp_mst_get_ufp_num_at_lct_from_rad(u8 lct, u8 *rad)
         |                                                ~~~~^~~


vim +201 drivers/gpu/drm/display/drm_dp_mst_topology.c

   193	
   194	static int
   195	drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len)
   196	{
   197		int i;
   198		u8 unpacked_rad[16] = {};
   199	
   200		for (i = 0; i < lct; i++)
 > 201			unpacked_rad[i] = drm_dp_mst_get_ufp_num_at_lct_from_rad(i + 1, rad);
   202	
   203		/* TODO: Eventually add something to printk so we can format the rad
   204		 * like this: 1.2.3
   205		 */
   206		return snprintf(out, len, "%*phC", lct, unpacked_rad);
   207	}
   208	

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