lkml.org 
[lkml]   [2021]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH v2 1/2] of: platform: Make sure bus only devices get probed
From
fw_devlink could end up creating device links for bus only devices.
However, bus only devices don't get probed and can block probe() or
sync_state() [1] call backs of other devices. To avoid this, set up
these devices to get probed by the simple-pm-bus.

[1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/
Signed-off-by: Saravana Kannan <saravanak@google.com>
Tested-by: Saravana Kannan <saravanak@google.com>
---
drivers/of/platform.c | 45 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 74afbb7a4f5e..b010e2310131 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -97,6 +97,48 @@ static void of_device_make_bus_id(struct device *dev)
}
}

+/**
+ * of_match_only_simple_bus - Check if a device node is only a simple bus
+ * @np: device node to check
+ *
+ * A simple bus in this context is defined as a transparent bus whose child
+ * devices are automatically populated but has no hardware specific
+ * functionality.
+ *
+ * Returns true if the device node is only a simple bus and can never match
+ * with any other specific driver. Otherwise, returns false.
+ */
+static bool of_match_only_simple_bus(struct device_node *np)
+{
+ /* List of buses that don't have an explicit driver. */
+ static const char * const of_simple_bus_table[] = {
+ "simple-bus",
+ "simple-mfd",
+ "isa",
+ "arm,amba-bus",
+ };
+ const char *cp;
+ struct property *prop;
+ int i;
+
+ prop = of_find_property(np, "compatible", NULL);
+ for (cp = of_prop_next_string(prop, NULL); cp;
+ cp = of_prop_next_string(prop, cp)) {
+ bool match = false;
+ const char *bus = of_simple_bus_table[i];
+
+ for (i = 0; i < ARRAY_SIZE(of_simple_bus_table); i++)
+ if (!of_compat_cmp(cp, bus, strlen(bus))) {
+ match = true;
+ break;
+ }
+ if (!match)
+ return false;
+ }
+
+ return true;
+}
+
/**
* of_device_alloc - Allocate and initialize an of_device
* @np: device node to assign to device
@@ -143,6 +185,9 @@ struct platform_device *of_device_alloc(struct device_node *np,
dev->dev.fwnode = &np->fwnode;
dev->dev.parent = parent ? : &platform_bus;

+ if (of_match_only_simple_bus(np))
+ dev->driver_override = "simple-pm-bus";
+
if (bus_id)
dev_set_name(&dev->dev, "%s", bus_id);
else
--
2.33.0.153.gba50c8fa24-goog
\
 
 \ /
  Last update: 2021-09-03 01:07    [W:0.097 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site