From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> Some discussion occured on previous posting. https://lore.kernel.org/linux-iio/20240223124432.26443-1-Jonathan.Cameron@xxxxxxxxxx/ Summary: * fwnode conversions should be considered when applying this infrastructure to a driver. Perhaps better to move directly to the generic FW property handling rather than improve existing of specific code. * There are lots of potential places to use this based on detections from Julia's coccinelle scripts linked below. The equivalent device_for_each_child_node_scoped() series for fwnode will be queued up in IIO for the merge window shortly as it has gathered sufficient tags. Hopefully the precdent set there for the approach will reassure people that instantiating the child variable inside the macro definition is the best approach. https://lore.kernel.org/linux-iio/20240217164249.921878-1-jic23@xxxxxxxxxx/ v2: Andy suggested most of the original converted set should move to generic fwnode / property.h handling. Within IIO that was a reasonable observation given we've been trying to move away from firmware specific handling for some time. Patches making that change to appropriate drivers posted. As we discussed there are cases which are not suitable for such conversion and this infrastructure still provides clear benefits for them. Ideally it would be good if this introductory series adding the infrastructure makes the 6.9 merge window. There are no dependencies on work queued in the IIO tree, so this can go via devicetree if the maintainers would prefer. I've had some off list messages asking when this would be merged, as there is interest in building on it next cycle for other parts of the kernel (where conversion to fwnode handling may be less appropriate). The outputs of Julia's scripts linked below show how widely this can be easily applied and give a conservative estimate of the complexity reduction and code savings. In some cases those drivers should move to fwnode and use the equivalent infrastructure there, but many will be unsuitable for conversion so this is still good win. Edited cover letter from v1: Thanks to Julia Lawal who also posted coccinelle for both types (loop and non loop cases) https://lore.kernel.org/all/alpine.DEB.2.22.394.2401312234250.3245@hadrien/ https://lore.kernel.org/all/alpine.DEB.2.22.394.2401291455430.8649@hadrien/ The cover letter of the RFC includes information on the various approaches considered. https://lore.kernel.org/all/20240128160542.178315-1-jic23@xxxxxxxxxx/ Whilst these macros produce nice reductions in complexity the loops still have the unfortunate side effect of hiding the local declaration of a struct device_node * which is then used inside the loop. Julia suggested making that a little more visible via #define for_each_child_of_node_scoped(parent, struct device_node *, child) but in discussion we both expressed that this doesn't really make things all that clear either so I haven't adopted this suggestion. Jonathan Cameron (4): of: Add cleanup.h based auto release via __free(device_node) markings. of: Introduce for_each_*_child_of_node_scoped() to automate of_node_put() handling of: unittest: Use for_each_child_of_node_scoped() iio: adc: rcar-gyroadc: use for_each_available_child_node_scoped() drivers/iio/adc/rcar-gyroadc.c | 21 ++++++--------------- drivers/of/unittest.c | 11 +++-------- include/linux/of.h | 15 +++++++++++++++ 3 files changed, 24 insertions(+), 23 deletions(-) -- 2.44.0
