[linux-next:master 2966/3989] drivers/gpu/drm/bridge/waveshare-dsi.c:70:5-15: WARNING: Unsigned expression compared with zero: dsi -> lanes < 0

[linux-next:master 2966/3989] drivers/gpu/drm/bridge/waveshare-dsi.c:70:5-15: WARNING: Unsigned expression compared with zero: dsi -> lanes < 0

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Marek Vasut <marek.vasut+renesas@mailbox.org>
CC: Luca Ceresoli <luca.ceresoli@bootlin.com>
CC: Joseph Guo <qijian.guo@nxp.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   fc7b1a72c6cd5cbbd989c6c32a6486e3e4e3594d
commit: fca11428425e92bf21d4a7f5865708c5e64430e4 [2966/3989] drm/bridge: waveshare-dsi: Add support for 1..4 DSI data lanes
:::::: branch date: 23 hours ago
:::::: commit date: 2 days ago
config: powerpc64-randconfig-r054-20260305 (https://download.01.org/0day-ci/archive/20260305/202603052201.P6ZmB8VT-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 8.5.0

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>
| Reported-by: Julia Lawall <julia.lawall@inria.fr>
| Closes: https://lore.kernel.org/r/202603052201.P6ZmB8VT-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/gpu/drm/bridge/waveshare-dsi.c:70:5-15: WARNING: Unsigned expression compared with zero: dsi -> lanes < 0

vim +70 drivers/gpu/drm/bridge/waveshare-dsi.c

dbdea37add132a Joseph Guo  2025-08-06  38  
dbdea37add132a Joseph Guo  2025-08-06  39  static int ws_bridge_attach_dsi(struct ws_bridge *ws)
dbdea37add132a Joseph Guo  2025-08-06  40  {
dbdea37add132a Joseph Guo  2025-08-06  41  	const struct mipi_dsi_device_info info = {
dbdea37add132a Joseph Guo  2025-08-06  42  		.type = "ws-bridge",
dbdea37add132a Joseph Guo  2025-08-06  43  		.channel = 0,
dbdea37add132a Joseph Guo  2025-08-06  44  		.node = NULL,
dbdea37add132a Joseph Guo  2025-08-06  45  	};
dbdea37add132a Joseph Guo  2025-08-06  46  	struct device_node *dsi_host_node;
dbdea37add132a Joseph Guo  2025-08-06  47  	struct device *dev = ws->dev;
dbdea37add132a Joseph Guo  2025-08-06  48  	struct mipi_dsi_device *dsi;
dbdea37add132a Joseph Guo  2025-08-06  49  	struct mipi_dsi_host *host;
dbdea37add132a Joseph Guo  2025-08-06  50  	int ret;
dbdea37add132a Joseph Guo  2025-08-06  51  
dbdea37add132a Joseph Guo  2025-08-06  52  	dsi_host_node = of_graph_get_remote_node(dev->of_node, 0, 0);
dbdea37add132a Joseph Guo  2025-08-06  53  	if (!dsi_host_node) {
dbdea37add132a Joseph Guo  2025-08-06  54  		dev_err(dev, "Failed to get remote port\n");
dbdea37add132a Joseph Guo  2025-08-06  55  		return -ENODEV;
dbdea37add132a Joseph Guo  2025-08-06  56  	}
dbdea37add132a Joseph Guo  2025-08-06  57  	host = of_find_mipi_dsi_host_by_node(dsi_host_node);
dbdea37add132a Joseph Guo  2025-08-06  58  	of_node_put(dsi_host_node);
dbdea37add132a Joseph Guo  2025-08-06  59  	if (!host)
dbdea37add132a Joseph Guo  2025-08-06  60  		return dev_err_probe(dev, -EPROBE_DEFER, "Failed to find dsi_host\n");
dbdea37add132a Joseph Guo  2025-08-06  61  
dbdea37add132a Joseph Guo  2025-08-06  62  	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
dbdea37add132a Joseph Guo  2025-08-06  63  	if (IS_ERR(dsi))
dbdea37add132a Joseph Guo  2025-08-06  64  		return dev_err_probe(dev, PTR_ERR(dsi), "Failed to create dsi device\n");
dbdea37add132a Joseph Guo  2025-08-06  65  
dbdea37add132a Joseph Guo  2025-08-06  66  	dsi->mode_flags = MIPI_DSI_MODE_VIDEO_HSE | MIPI_DSI_MODE_VIDEO |
dbdea37add132a Joseph Guo  2025-08-06  67  			  MIPI_DSI_CLOCK_NON_CONTINUOUS;
dbdea37add132a Joseph Guo  2025-08-06  68  	dsi->format = MIPI_DSI_FMT_RGB888;
fca11428425e92 Marek Vasut 2026-01-15  69  	dsi->lanes = drm_of_get_data_lanes_count_ep(dev->of_node, 0, 0, 1, 4);
fca11428425e92 Marek Vasut 2026-01-15 @70  	if (dsi->lanes < 0) {
fca11428425e92 Marek Vasut 2026-01-15  71  		dev_warn(dev, "Invalid or missing DSI lane count %d, falling back to 2 lanes\n",
fca11428425e92 Marek Vasut 2026-01-15  72  			 dsi->lanes);
fca11428425e92 Marek Vasut 2026-01-15  73  		dsi->lanes = 2;	/* Old DT backward compatibility */
fca11428425e92 Marek Vasut 2026-01-15  74  	}
dbdea37add132a Joseph Guo  2025-08-06  75  
dbdea37add132a Joseph Guo  2025-08-06  76  	ret = devm_mipi_dsi_attach(dev, dsi);
dbdea37add132a Joseph Guo  2025-08-06  77  	if (ret < 0)
dbdea37add132a Joseph Guo  2025-08-06  78  		return dev_err_probe(dev, ret, "Failed to attach dsi to host\n");
dbdea37add132a Joseph Guo  2025-08-06  79  
dbdea37add132a Joseph Guo  2025-08-06  80  	return 0;
dbdea37add132a Joseph Guo  2025-08-06  81  }
dbdea37add132a Joseph Guo  2025-08-06  82  

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