[PATCH 0/6] use device_for_each_child_node() to access device child nodes

Javier Carrasco
2024-07-06T15:23:54Z

This series aims to clarify the use cases of:

- device_for_each_child_node[_scoped]()
- fwnode_for_each_available_child_node[_scoped]()

to access firmware nodes.

There have been multiple discussions [1][2] about what the first macro
implies in the sense of availability, and a number of users have opted
for the second macro in cases where the first one should have been
preferred.

The second macro is intended to be used over child nodes of a firmware
node, not direct child nodes of the device node. Instead, those users
retrieve the fwnode member from the device struct just to have access to
a macro that explicitly indicates node availability.

That workaround is not necessary because `device_for_each_child_node()`
implies availability for the existing backends (ACPI, DT, swnode).

This series does not cover other points discussed in [2] like addressing
uses of `fwnode_for_each_child_node()` where `device_*` should have been
used, using the `_avaialble_` variant of the fwnode loop whenever
possible, or adding new `_scoped` macros. Such points will be covered by
subsequent series to keep focus on the "availability" issue.

The conversion has been validated with an LTC2992 hwmon sensor, which is
one of the affected drivers. The rest of the drivers could only be
compiled and checked with static-analysis tools.

Link: https://lore.kernel.org/all/20211205190101.26de4a57@jic23-huawei/ [1]
Link: https://lore.kernel.org/all/20240523-fwnode_for_each_available_child_node_scoped-v2-0-701f3a03f2fb@gmail.com/ [2]

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
Javier Carrasco (6):
device property: document device_for_each_child_node macro
hwmon: (ltc2992) use device_for_each_child_node_scoped() to access child nodes
leds: bd2606mvv: use device_for_each_child_node() to access device child nodes
leds: is31fl319x: use device_for_each_child_node_scoped() to access child nodes
leds: pca995x: use device_for_each_child_node() to access device child nodes
net: mvpp2: use device_for_each_child_node() to access device child nodes

drivers/hwmon/ltc2992.c | 19 ++++----------
drivers/leds/leds-bd2606mvv.c | 7 +++--
drivers/leds/leds-is31fl319x.c | 34 ++++++++-----------------
drivers/leds/leds-pca995x.c | 15 ++++-------
drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 13 +++-------
include/linux/property.h | 10 ++++++++
6 files changed, 38 insertions(+), 60 deletions(-)
---
base-commit: 0b58e108042b0ed28a71cd7edf5175999955b233
change-id: 20240701-device_for_each_child_node-available-1c1eca4b6495

Best regards,
--
Javier Carrasco <javier.carrasco.cruz@gmail.com>