[PATCH v5 2/6] driver core: Set deferred_probe_timeout to a longer default if CONFIG_MODULES is set

When using modules, its common for the modules not to be loaded
until quite late by userland. With the current code,
driver_deferred_probe_check_state() will stop returning
EPROBE_DEFER after late_initcall, which can cause module
dependency resolution to fail after that.

So allow a longer window of 30 seconds (picked somewhat
arbitrarily, but influenced by the similar regulator core
timeout value) in the case where modules are enabled.

Cc: Rob Herring <robh@kernel.org>
Cc: "Rafael J. Wysocki" <redacted>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Ulf Hansson <redacted>
Cc: Pavel Machek <redacted>
Cc: Len Brown <redacted>
Cc: Todd Kjos <redacted>
Cc: Saravana Kannan <redacted>
Cc: Bjorn Andersson <redacted>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Thierry Reding <redacted>
Cc: Linus Walleij <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-pm@vger.kernel.org
Reviewed-by: Rafael J. Wysocki <redacted>
Reviewed-by: Bjorn Andersson <redacted>
Signed-off-by: John Stultz <redacted>
---
v4:
* Split out into its own patch as suggested by Mark
* Made change conditional on CONFIG_MODULES
---
 drivers/base/dd.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index d75b34de6964..fe26f2574a6d 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c

@@ -224,7 +224,16 @@ static int deferred_devs_show(struct seq_file *s, void *data)
 }
 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 
+#ifdef CONFIG_MODULES
+/*
+ * In the case of modules, set the default probe timeout to
+ * 30 seconds to give userland some time to load needed modules
+ */
+static int deferred_probe_timeout = 30;
+#else
+/* In the case of !modules, no probe timeout needed */
 static int deferred_probe_timeout = -1;
+#endif
 static int __init deferred_probe_timeout_setup(char *str)
 {
 	int timeout;

-- 
2.17.1