From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: gregkh@linuxfoundation.org, rafael.j.wysocki@intel.com,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>
Cc: f.fainelli@gmail.com, linux-rpi-kernel@lists.infradead.org,
saravanak@google.com, u.kleine-koenig@pengutronix.de,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC] of/platform: Create device link between simple-mfd and its children
Date: Thu, 15 Oct 2020 13:43:46 +0200 [thread overview]
Message-ID: <20201015114346.15743-1-nsaenzjulienne@suse.de> (raw)
'simple-mfd' usage implies there might be some kind of resource sharing
between the parent device and its children. By creating a device link
with DL_FLAG_AUTOREMOVE_CONSUMER we make sure that at no point in time
the parent device is unbound while leaving its children unaware that
some of their resources disappeared.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
Some questions:
- To what extent do we care about cleanly unbinding platform devices at
runtime? My rationale here is: "It's a platform device, for all you
know you might be unbinding someting essential to the system. So if
you're doing it, you better know what you're doing."
- Would this be an abuse of device links?
- If applying this to all simple-mfd devices is a bit too much, would
this be acceptable for a specific device setup. For example RPi4's
firmware interface (simple-mfd user) is passed to consumer drivers
trough a custom API (see rpi_firmware_get()). So, when unbound,
consumers are left with a firmware handle that points to nothing.
drivers/of/platform.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index b557a0fcd4ba..8d5b55b81764 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -390,8 +390,14 @@ static int of_platform_bus_create(struct device_node *bus,
}
dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
- if (!dev || !of_match_node(matches, bus))
- return 0;
+ if (!dev)
+ return 0;
+
+ if (parent && of_device_is_compatible(parent->of_node, "simple-mfd"))
+ device_link_add(&dev->dev, parent, DL_FLAG_AUTOREMOVE_CONSUMER);
+
+ if (!of_match_node(matches, bus))
+ return 0;
for_each_child_of_node(bus, child) {
pr_debug(" create child: %pOF\n", child);
--
2.28.0
next reply other threads:[~2020-10-15 11:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 11:43 Nicolas Saenz Julienne [this message]
2020-10-15 16:52 ` [RFC] of/platform: Create device link between simple-mfd and its children Saravana Kannan
2020-10-16 15:39 ` Nicolas Saenz Julienne
2020-10-16 14:38 ` Rob Herring
2020-10-16 15:26 ` Nicolas Saenz Julienne
2020-10-19 6:52 ` Uwe Kleine-König
2020-10-21 11:35 ` Nicolas Saenz Julienne
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