tools: add some extra help output about the expected input data

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

diff --git a/tools/ptraccel-debug.c b/tools/ptraccel-debug.c
index fcadcbc0d342589c5a9699506318c628b6d98e09..84a1221c432dea1c9a9a63cac7093f48c34461c5 100644 (file)
--- a/tools/ptraccel-debug.c
+++ b/tools/ptraccel-debug.c
@@ -182,6 +182,9 @@ usage(void)
               "If stdin is a pipe, mode defaults to 'sequence' and the pipe is read \n"
               "for delta coordinates\n"
               "\n"
+              "Delta coordinates passed into this tool must be in dpi as\n"
+              "specified by the --dpi argument\n"
+              "\n"
               "Output best viewed with gnuplot. See output for gnuplot commands\n");
 }