[PATCH v4 2/6] driver core: Set deferred_probe_timeout to a longer default if CONFIG_MODULES is set

[John Stultz]

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@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxx>
Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Todd Kjos <tkjos@xxxxxxxxxx>
Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Cc: Liam Girdwood <lgirdwood@xxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Thierry Reding <treding@xxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Change-Id: I9c5a02a54915ff53f9f14d49c601f41d7105e05e
---
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 bb383dca39c1..fa138f24e2d3 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