This is a note to let you know that I've just added the patch titled
drivers: bus: simple-pm-bus: Add support for probing simple bus only
to my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 98e96cf80045a383fcc47c58dd4e87b3ae587b3e Mon Sep 17 00:00:00 2001
From: Saravana Kannan <saravanak(a)google.com>
Date: Tue, 28 Sep 2021 17:07:33 -0700
Subject: drivers: bus: simple-pm-bus: Add support for probing simple bus only
devices
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, probe these
devices using the simple-pm-bus driver.
However, there are instances of devices that are not simple buses (they get
probed by their specific drivers) that also list the "simple-bus" (or other
bus only compatible strings) in their compatible property to automatically
populate their child devices. We still want these devices to get probed by
their specific drivers. So, we make sure this driver only probes devices
that are only buses.
[1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxH…
Fixes: c442a0d18744 ("driver core: Set fw_devlink to "permissive" behavior by default")
Cc: stable <stable(a)vger.kernel.org>
Cc: Rob Herring <robh+dt(a)kernel.org>
Tested-by: Saravana Kannan <saravanak(a)google.com>
Tested-by: Ulf Hansson <ulf.hansson(a)linaro.org>
Tested-by: Geert Uytterhoeven <geert+renesas(a)glider.be>
Tested-by: Damien Le Moal <damien.lemoal(a)wdc.com>
Signed-off-by: Saravana Kannan <saravanak(a)google.com>
Link: https://lore.kernel.org/r/20210929000735.585237-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/bus/simple-pm-bus.c | 42 ++++++++++++++++++++++++++++++++++---
1 file changed, 39 insertions(+), 3 deletions(-)
diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
index 01a3d0cd08ed..6b8d6257ed8a 100644
--- a/drivers/bus/simple-pm-bus.c
+++ b/drivers/bus/simple-pm-bus.c
@@ -13,11 +13,36 @@
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
-
static int simple_pm_bus_probe(struct platform_device *pdev)
{
- const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev);
- struct device_node *np = pdev->dev.of_node;
+ const struct device *dev = &pdev->dev;
+ const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
+ struct device_node *np = dev->of_node;
+ const struct of_device_id *match;
+
+ /*
+ * Allow user to use driver_override to bind this driver to a
+ * transparent bus device which has a different compatible string
+ * that's not listed in simple_pm_bus_of_match. We don't want to do any
+ * of the simple-pm-bus tasks for these devices, so return early.
+ */
+ if (pdev->driver_override)
+ return 0;
+
+ match = of_match_device(dev->driver->of_match_table, dev);
+ /*
+ * These are transparent bus devices (not simple-pm-bus matches) that
+ * have their child nodes populated automatically. So, don't need to
+ * do anything more. We only match with the device if this driver is
+ * the most specific match because we don't want to incorrectly bind to
+ * a device that has a more specific driver.
+ */
+ if (match && match->data) {
+ if (of_property_match_string(np, "compatible", match->compatible) == 0)
+ return 0;
+ else
+ return -ENODEV;
+ }
dev_dbg(&pdev->dev, "%s\n", __func__);
@@ -31,14 +56,25 @@ static int simple_pm_bus_probe(struct platform_device *pdev)
static int simple_pm_bus_remove(struct platform_device *pdev)
{
+ const void *data = of_device_get_match_data(&pdev->dev);
+
+ if (pdev->driver_override || data)
+ return 0;
+
dev_dbg(&pdev->dev, "%s\n", __func__);
pm_runtime_disable(&pdev->dev);
return 0;
}
+#define ONLY_BUS ((void *) 1) /* Match if the device is only a bus. */
+
static const struct of_device_id simple_pm_bus_of_match[] = {
{ .compatible = "simple-pm-bus", },
+ { .compatible = "simple-bus", .data = ONLY_BUS },
+ { .compatible = "simple-mfd", .data = ONLY_BUS },
+ { .compatible = "isa", .data = ONLY_BUS },
+ { .compatible = "arm,amba-bus", .data = ONLY_BUS },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match);
--
2.33.0
This is a note to let you know that I've just added the patch titled
driver core: Reject pointless SYNC_STATE_ONLY device links
to my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From f729a592adb6760013c3e48622a5bf256b992452 Mon Sep 17 00:00:00 2001
From: Saravana Kannan <saravanak(a)google.com>
Date: Wed, 29 Sep 2021 12:05:49 -0700
Subject: driver core: Reject pointless SYNC_STATE_ONLY device links
SYNC_STATE_ONLY device links intentionally allow cycles because cyclic
sync_state() dependencies are valid and necessary.
However a SYNC_STATE_ONLY device link where the consumer and the supplier
are the same device is pointless because the device link would be deleted
as soon as the device probes (because it's also the consumer) and won't
affect when the sync_state() callback is called. It's a waste of CPU cycles
and memory to create this device link. So reject any attempts to create
such a device link.
Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag")
Cc: stable <stable(a)vger.kernel.org>
Reported-by: Ulf Hansson <ulf.hansson(a)linaro.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson(a)linaro.org>
Signed-off-by: Saravana Kannan <saravanak(a)google.com>
Link: https://lore.kernel.org/r/20210929190549.860541-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/base/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 15986cc2fe5e..249da496581a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -687,7 +687,8 @@ struct device_link *device_link_add(struct device *consumer,
{
struct device_link *link;
- if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS ||
+ if (!consumer || !supplier || consumer == supplier ||
+ flags & ~DL_ADD_VALID_FLAGS ||
(flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
(flags & DL_FLAG_SYNC_STATE_ONLY &&
(flags & ~DL_FLAG_INFERRED) != DL_FLAG_SYNC_STATE_ONLY) ||
--
2.33.0