It seems that commit cc5848213329 ("perf help: Remove use of die and
handle errors") caused the problem - it changed the initial value of
'help_format' from HELP_FORMAT_MAN to HELP_FORMAT_NONE.
The following patch works well for me:
diff --git a/tools/perf/builtin-help.c b/tools/perf/builtin-help.c
index 411ee5664e98..178b88ae3d2f 100644
--- a/tools/perf/builtin-help.c
+++ b/tools/perf/builtin-help.c
@@ -414,7 +414,7 @@ static int show_html_page(const char *perf_cmd)
int cmd_help(int argc, const char **argv, const char *prefix __maybe_unused)
{
bool show_all = false;
- enum help_format help_format = HELP_FORMAT_NONE;
+ enum help_format help_format = HELP_FORMAT_MAN;
struct option builtin_help_options[] = {
OPT_BOOLEAN('a', "all", &show_all, "print all available commands"),
OPT_SET_UINT('m', "man", &help_format, "show man page", HELP_FORMAT_MAN),