From: Ethan Tidmore Date: Sat, 7 Mar 2026 03:32:45 +0000 (-0600) Subject: drm/bridge: waveshare-dsi: Fix signedness bug X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a469749640fbcd2f49ab05fb83cca3da07f35ee3;p=thirdparty%2Fkernel%2Flinux.git drm/bridge: waveshare-dsi: Fix signedness bug The function drm_of_get_data_lanes_count_ep() returns negative error codes and dsi->lanes is an unsigned integer, so the check (dsi->lanes < 0) is always impossible. Make the return value of drm_of_get_data_lanes_count_ep() be assigned to ret, check for error, and then assign dsi->lanes to ret. Detected by Smatch: drivers/gpu/drm/bridge/waveshare-dsi.c:70 ws_bridge_attach_dsi() warn: unsigned 'dsi->lanes' is never less than zero. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202603060341.hNj0pl9L-lkp@intel.com/ Fixes: fca11428425e9 ("drm/bridge: waveshare-dsi: Add support for 1..4 DSI data lanes") Signed-off-by: Ethan Tidmore Reviewed-by: Luca Ceresoli Reviewed-by: Marek Vasut Link: https://patch.msgid.link/20260307033245.71666-1-ethantidmore06@gmail.com Signed-off-by: Luca Ceresoli --- diff --git a/drivers/gpu/drm/bridge/waveshare-dsi.c b/drivers/gpu/drm/bridge/waveshare-dsi.c index 0497c7ecbc7a5..32d40414adb9f 100644 --- a/drivers/gpu/drm/bridge/waveshare-dsi.c +++ b/drivers/gpu/drm/bridge/waveshare-dsi.c @@ -66,11 +66,13 @@ static int ws_bridge_attach_dsi(struct ws_bridge *ws) dsi->mode_flags = MIPI_DSI_MODE_VIDEO_HSE | MIPI_DSI_MODE_VIDEO | MIPI_DSI_CLOCK_NON_CONTINUOUS; dsi->format = MIPI_DSI_FMT_RGB888; - dsi->lanes = drm_of_get_data_lanes_count_ep(dev->of_node, 0, 0, 1, 4); - if (dsi->lanes < 0) { + ret = drm_of_get_data_lanes_count_ep(dev->of_node, 0, 0, 1, 4); + if (ret < 0) { dev_warn(dev, "Invalid or missing DSI lane count %d, falling back to 2 lanes\n", - dsi->lanes); + ret); dsi->lanes = 2; /* Old DT backward compatibility */ + } else { + dsi->lanes = ret; } ret = devm_mipi_dsi_attach(dev, dsi);