Re: [PATCH] cxl/region: Allow 6 & 12 way regions on 3-way HB interleaves

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

Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 2bb67004903cfd35710750654669a77e7223fcd1]

url:    https://github.com/intel-lab-lkp/linux/commits/alison-schofield-intel-com/cxl-region-Allow-6-12-way-regions-on-3-way-HB-interleaves/20250225-080107
base:   2bb67004903cfd35710750654669a77e7223fcd1
patch link:    https://lore.kernel.org/r/20250224235817.2259508-1-alison.schofield%40intel.com
patch subject: [PATCH] cxl/region: Allow 6 & 12 way regions on 3-way HB interleaves
config: riscv-randconfig-001-20250225 (https://download.01.org/0day-ci/archive/20250225/202502251245.NLuc888W-lkp@intel.com/config)
compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250225/202502251245.NLuc888W-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/202502251245.NLuc888W-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/cxl/core/region.c:1852: warning: Function parameter or struct member 'multiple' not described in 'cxl_calc_interleave_pos'


vim +1852 drivers/cxl/core/region.c

a3e00c964fb9439 Alison Schofield 2023-10-27  1834  
a3e00c964fb9439 Alison Schofield 2023-10-27  1835  /**
a3e00c964fb9439 Alison Schofield 2023-10-27  1836   * cxl_calc_interleave_pos() - calculate an endpoint position in a region
a3e00c964fb9439 Alison Schofield 2023-10-27  1837   * @cxled: endpoint decoder member of given region
a3e00c964fb9439 Alison Schofield 2023-10-27  1838   *
a3e00c964fb9439 Alison Schofield 2023-10-27  1839   * The endpoint position is calculated by traversing the topology from
a3e00c964fb9439 Alison Schofield 2023-10-27  1840   * the endpoint to the root decoder and iteratively applying this
a3e00c964fb9439 Alison Schofield 2023-10-27  1841   * calculation:
a3e00c964fb9439 Alison Schofield 2023-10-27  1842   *
a3e00c964fb9439 Alison Schofield 2023-10-27  1843   *    position = position * parent_ways + parent_pos;
a3e00c964fb9439 Alison Schofield 2023-10-27  1844   *
a3e00c964fb9439 Alison Schofield 2023-10-27  1845   * ...where @position is inferred from switch and root decoder target lists.
a3e00c964fb9439 Alison Schofield 2023-10-27  1846   *
a3e00c964fb9439 Alison Schofield 2023-10-27  1847   * Return: position >= 0 on success
a3e00c964fb9439 Alison Schofield 2023-10-27  1848   *	   -ENXIO on failure
a3e00c964fb9439 Alison Schofield 2023-10-27  1849   */
22639743643957e Alison Schofield 2025-02-24  1850  static int cxl_calc_interleave_pos(struct cxl_endpoint_decoder *cxled,
22639743643957e Alison Schofield 2025-02-24  1851  				   int multiple)
a3e00c964fb9439 Alison Schofield 2023-10-27 @1852  {
a3e00c964fb9439 Alison Schofield 2023-10-27  1853  	struct cxl_port *iter, *port = cxled_to_port(cxled);
a3e00c964fb9439 Alison Schofield 2023-10-27  1854  	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
a3e00c964fb9439 Alison Schofield 2023-10-27  1855  	struct range *range = &cxled->cxld.hpa_range;
a3e00c964fb9439 Alison Schofield 2023-10-27  1856  	int parent_ways = 0, parent_pos = 0, pos = 0;
a3e00c964fb9439 Alison Schofield 2023-10-27  1857  	int rc;
a3e00c964fb9439 Alison Schofield 2023-10-27  1858  
a3e00c964fb9439 Alison Schofield 2023-10-27  1859  	/*
a3e00c964fb9439 Alison Schofield 2023-10-27  1860  	 * Example: the expected interleave order of the 4-way region shown
a3e00c964fb9439 Alison Schofield 2023-10-27  1861  	 * below is: mem0, mem2, mem1, mem3
a3e00c964fb9439 Alison Schofield 2023-10-27  1862  	 *
a3e00c964fb9439 Alison Schofield 2023-10-27  1863  	 *		  root_port
a3e00c964fb9439 Alison Schofield 2023-10-27  1864  	 *                 /      \
a3e00c964fb9439 Alison Schofield 2023-10-27  1865  	 *      host_bridge_0    host_bridge_1
a3e00c964fb9439 Alison Schofield 2023-10-27  1866  	 *        |    |           |    |
a3e00c964fb9439 Alison Schofield 2023-10-27  1867  	 *       mem0 mem1        mem2 mem3
a3e00c964fb9439 Alison Schofield 2023-10-27  1868  	 *
a3e00c964fb9439 Alison Schofield 2023-10-27  1869  	 * In the example the calculator will iterate twice. The first iteration
a3e00c964fb9439 Alison Schofield 2023-10-27  1870  	 * uses the mem position in the host-bridge and the ways of the host-
a3e00c964fb9439 Alison Schofield 2023-10-27  1871  	 * bridge to generate the first, or local, position. The second
a3e00c964fb9439 Alison Schofield 2023-10-27  1872  	 * iteration uses the host-bridge position in the root_port and the ways
a3e00c964fb9439 Alison Schofield 2023-10-27  1873  	 * of the root_port to refine the position.
a3e00c964fb9439 Alison Schofield 2023-10-27  1874  	 *
a3e00c964fb9439 Alison Schofield 2023-10-27  1875  	 * A trace of the calculation per endpoint looks like this:
a3e00c964fb9439 Alison Schofield 2023-10-27  1876  	 * mem0: pos = 0 * 2 + 0    mem2: pos = 0 * 2 + 0
a3e00c964fb9439 Alison Schofield 2023-10-27  1877  	 *       pos = 0 * 2 + 0          pos = 0 * 2 + 1
a3e00c964fb9439 Alison Schofield 2023-10-27  1878  	 *       pos: 0                   pos: 1
a3e00c964fb9439 Alison Schofield 2023-10-27  1879  	 *
a3e00c964fb9439 Alison Schofield 2023-10-27  1880  	 * mem1: pos = 0 * 2 + 1    mem3: pos = 0 * 2 + 1
a3e00c964fb9439 Alison Schofield 2023-10-27  1881  	 *       pos = 1 * 2 + 0          pos = 1 * 2 + 1
a3e00c964fb9439 Alison Schofield 2023-10-27  1882  	 *       pos: 2                   pos = 3
a3e00c964fb9439 Alison Schofield 2023-10-27  1883  	 *
a3e00c964fb9439 Alison Schofield 2023-10-27  1884  	 * Note that while this example is simple, the method applies to more
a3e00c964fb9439 Alison Schofield 2023-10-27  1885  	 * complex topologies, including those with switches.
a3e00c964fb9439 Alison Schofield 2023-10-27  1886  	 */
a3e00c964fb9439 Alison Schofield 2023-10-27  1887  
a3e00c964fb9439 Alison Schofield 2023-10-27  1888  	/* Iterate from endpoint to root_port refining the position */
a3e00c964fb9439 Alison Schofield 2023-10-27  1889  	for (iter = port; iter; iter = next_port(iter)) {
a3e00c964fb9439 Alison Schofield 2023-10-27  1890  		if (is_cxl_root(iter))
a3e00c964fb9439 Alison Schofield 2023-10-27  1891  			break;
a3e00c964fb9439 Alison Schofield 2023-10-27  1892  
a3e00c964fb9439 Alison Schofield 2023-10-27  1893  		rc = find_pos_and_ways(iter, range, &parent_pos, &parent_ways);
a3e00c964fb9439 Alison Schofield 2023-10-27  1894  		if (rc)
a3e00c964fb9439 Alison Schofield 2023-10-27  1895  			return rc;
a3e00c964fb9439 Alison Schofield 2023-10-27  1896  
22639743643957e Alison Schofield 2025-02-24  1897  		if (multiple > 1 && is_cxl_root(next_port(iter))) {
22639743643957e Alison Schofield 2025-02-24  1898  			pos = pos + multiple * parent_pos;
22639743643957e Alison Schofield 2025-02-24  1899  			break;
22639743643957e Alison Schofield 2025-02-24  1900  		}
22639743643957e Alison Schofield 2025-02-24  1901  
a3e00c964fb9439 Alison Schofield 2023-10-27  1902  		pos = pos * parent_ways + parent_pos;
a3e00c964fb9439 Alison Schofield 2023-10-27  1903  	}
a3e00c964fb9439 Alison Schofield 2023-10-27  1904  
a3e00c964fb9439 Alison Schofield 2023-10-27  1905  	dev_dbg(&cxlmd->dev,
a3e00c964fb9439 Alison Schofield 2023-10-27  1906  		"decoder:%s parent:%s port:%s range:%#llx-%#llx pos:%d\n",
a3e00c964fb9439 Alison Schofield 2023-10-27  1907  		dev_name(&cxled->cxld.dev), dev_name(cxlmd->dev.parent),
a3e00c964fb9439 Alison Schofield 2023-10-27  1908  		dev_name(&port->dev), range->start, range->end, pos);
a3e00c964fb9439 Alison Schofield 2023-10-27  1909  
a3e00c964fb9439 Alison Schofield 2023-10-27  1910  	return pos;
a3e00c964fb9439 Alison Schofield 2023-10-27  1911  }
a3e00c964fb9439 Alison Schofield 2023-10-27  1912  

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