linux-kernel - [RFC][PATCH] pinctrl: Rework driver_deferred_probe_check_state() evaluation since default timeout has changed

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Date:   Sat,  8 Aug 2020 04:35:12 +0000
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     John Stultz <john.stultz@...aro.org>, linux-pm@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Thierry Reding <treding@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Saravana Kannan <saravanak@...gle.com>,
        Todd Kjos <tkjos@...gle.com>, Len Brown <len.brown@...el.com>,
        Pavel Machek <pavel@....cz>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Kevin Hilman <khilman@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Rob Herring <robh@...nel.org>
Subject: [RFC][PATCH] pinctrl: Rework driver_deferred_probe_check_state() evaluation since default timeout has changed

In commit bec6c0ecb243 ("pinctrl: Remove use of
driver_deferred_probe_check_state_continue()"), we removed the
use of driver_deferred_probe_check_state_continue() which
effectively never returned -ETIMED_OUT, with the
driver_deferred_probe_check_state() function that had been
reworked to properly return ETIMED_OUT when the deferred probe
timeout expired. Along with that change, we set the default
timeout to 30 seconds.

However, since moving the timeout to 30 seconds caused some
issues for some users with optional dt links, we set the
default timeout back to zero - see commit ce68929f07de ("driver
core: Revert default driver_deferred_probe_timeout value to 0")

This in essence changed the behavior of the pinctrl's usage
of driver_deferred_probe_check_state(), as it now would return
ETIMED_OUT by default. Thierry reported this caused problems with
resume on tegra platforms.

Thus this patch tweaks the pinctrl logic so that it behaves as
before. If modules are enabled, we'll only return EPROBE_DEFERRED
while we're missing drivers linked in the DT.

Cc: linux-pm@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Linus Walleij <linus.walleij@...aro.org>
Cc: Thierry Reding <treding@...dia.com>
Cc: Mark Brown <broonie@...nel.org>
Cc: Liam Girdwood <lgirdwood@...il.com>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
Cc: Saravana Kannan <saravanak@...gle.com>
Cc: Todd Kjos <tkjos@...gle.com>
Cc: Len Brown <len.brown@...el.com>
Cc: Pavel Machek <pavel@....cz>
Cc: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Kevin Hilman <khilman@...nel.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Rob Herring <robh@...nel.org>
Fixes: bec6c0ecb243 ("pinctrl: Remove use of driver_deferred_probe_check_state_continue()")
Fixes: ce68929f07de ("driver core: Revert default driver_deferred_probe_timeout value to 0")
Reported-by: Thierry Reding <thierry.reding@...il.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/pinctrl/devicetree.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index c6fe7d64c913..09ddf567ccb4 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -129,9 +129,8 @@ static int dt_to_map_one_config(struct pinctrl *p,
 		if (!np_pctldev || of_node_is_root(np_pctldev)) {
 			of_node_put(np_pctldev);
 			ret = driver_deferred_probe_check_state(p->dev);
-			/* keep deferring if modules are enabled unless we've timed out */
-			if (IS_ENABLED(CONFIG_MODULES) && !allow_default &&
-			    (ret == -ENODEV))
+			/* keep deferring if modules are enabled */
+			if (IS_ENABLED(CONFIG_MODULES) && !allow_default)
 				ret = -EPROBE_DEFER;
 			return ret;
 		}
-- 
2.17.1