On Wed, Dec 11, 2024 at 09:58:26PM +0000, Jonathan Cameron wrote: > On Tue, 10 Dec 2024 16:48:57 -0600 > Chris Morgan <macroalpha82@xxxxxxxxx> wrote: > > > From: Chris Morgan <macromorgan@xxxxxxxxxxx> > > > > After performing a git bisect, I identified a commit that broke the > > battery and charger driver for my AXP717 PMIC. This was caused by > > commit e37ec3218870 ("mfd: axp20x: Allow multiple regulators"). > > > > After digging into it, it appears when mfd_add_devices was called with > > a platform ID of PLATFORM_DEVID_NONE, the devm_iio_channel_get() call > > made by the various AXP20X power drivers would not be able to generate > > a dev_name(dev) for some reason, and the iio_channel_get() call used in > > the devm_ helper would fall back to making a iio_channel_get_sys() > > call. After the platform ID was updated, now iio_channel_get() is no > > longer falling back to iio_channel_get_sys(). At least this is my > > limited understanding of what happened. > > The dev_name(dev) not getting a name doesn't sound quite right to me. > > Time to look at the ancient creaking ghost that is the iio_map handling. > > struct iio_channel *iio_channel_get(struct device *dev, > const char *channel_name) > { > const char *name = dev ? dev_name(dev) : NULL; > struct iio_channel *channel; > > if (dev) { > channel = fwnode_iio_channel_get_by_name(dev_fwnode(dev), > channel_name); > if (!IS_ERR(channel) || PTR_ERR(channel) != -ENODEV) > return channel; > } > > return iio_channel_get_sys(name, channel_name); > } > EXPORT_SYMBOL_GPL(iio_channel_get); > > We didn't invent the relevant phandle stuff in DT via the patch you point at > so all that matters is what gets passed to that iio_channel_get_sys() > > So key here is that dev should be set, so we are passing dev_name(dev) into > iio_channel_get_sys() > I'm guessing that changed... > > Ah. The iio_maps in > https://elixir.bootlin.com/linux/v6.12.4/source/drivers/iio/adc/axp20x_adc.c#L158 > are our problem. Those hardcode the consumer_dev name. The fix just changed > those names. Back when this infrastructure was written we were in the world of > board files, so everything was hard coded in them - or in an MFD like this > it was treated as a singleton device. > > So as to how to fix it... Assuming the new device names are the same for all > the mfd parts that make up each pmic, then you should be able to figure out the > extra the number and build the channel maps to allow you to find the numbered > devices. Is there a way to figure out the device number at runtime? The issue is each time the device attempts to probe and fails, the device number increments, making it a "hitting a moving target" problem. Thank you, Chris > > That's a lot lighter change than moving over to DT based phandles for all this. > (which is the modern way to handle it). > > As a cheeky check, just edit those maps to whatever IDs you have and see > if it works. Probably not an upstreamable solution but will confirm we have > it correct. > > Your patch works because we allow for some fuzzy matching (I can't remember > why) that doesn't use the consumer device name. > That works as long as there is only one instance. I'm guessing all this > mess came about because someone has a board with two of these devices. On such > a board we need the precise matching including the device name. > > Jonathan > > > > > To fix this, I added a new devm_ helper of devm_iio_channel_get_sys() > > that directly calls iio_channel_get_sys(), and I updated all the > > affected drivers with the new routine. I then no longer experienced > > any issues with the drivers on my devices. > > > > Chris Morgan (2): > > iio: core: Add devm_ API for iio_channel_get_sys > > power: supply: axp20x: Use devm_iio_channel_get_sys() for iio chans > > > > drivers/iio/inkern.c | 18 ++++++++++++++++++ > > drivers/power/supply/axp20x_ac_power.c | 4 ++-- > > drivers/power/supply/axp20x_battery.c | 16 ++++++++-------- > > drivers/power/supply/axp20x_usb_power.c | 6 +++--- > > include/linux/iio/consumer.h | 20 ++++++++++++++++++++ > > 5 files changed, 51 insertions(+), 13 deletions(-) > > >