Re: [RFC PATCH 0/6] Support ROHM BD96801 scalable PMIC

From: Matti Vaittinen
Date: Fri Apr 05 2024 - 05:19:58 EST


On 4/4/24 16:15, Matti Vaittinen wrote:
Hi Mark,

On 4/4/24 15:09, Mark Brown wrote:
On Thu, Apr 04, 2024 at 10:26:34AM +0300, Matti Vaittinen wrote:

1. Should we be able to have more than 1 IRQ domain / device?
2. Should regmap_irq support having more than 1 HWIRQ

I would expect each parent interrupt to show up as a separate remap_irq.

then it seems that reading the IRQ information from the /proc/interrupts
works as expected. Here I am making a wild guess that the name of the domain
is used as a key for some data-lookups, and having two domains with a same
name will either overwrite something or cause wrong domain data to be
fetched. (This is just guessing for now).

This was wrong guessing.

So if we arrange to supply a name when we register multiple domains
things should work fine?

After my latest findings, yes, I think so. How to do this correctly is beyond me though. The __irq_domain_create() seems to me that the name is meant to be the dt-node name when the controller is backed by a real dt-node. Naming of the irq_domain_alloc_named_fwnode() sounds to me like it is only intended to be used when there is no real fwnode. All suggestions appreciated. Using the:
irq_domain_update_bus_token(intb_domain, DOMAIN_BUS_WIRED);
feels like a dirty hack, and won't scale if there is more HWIRQs.

Thanks for taking the time to look at my questions :)
I have been debugging this thing whole day today, without getting too far :) It seems there is something beyond the name collision though.

After I tried adding '-1' to the end of the other domain name to avoid the debugfs name collision I managed to do couple of successful runs - after which I reported here that problem seems to be just the naming. Soon after sending that mail I hit the oops again even though the naming was fixed.

Further debugging shows that the desc->action->name for the last 28 'errb' IRQs get corrupted. This might point more to the IRQ requester side - so I need to further study the BD96801 driver side as well as the regulator_irq_helper. I'm having the creeping feeling that at the end of the day I need to find the guilty one from the mirror :)

I was not wrong on this one. The regulator_irq_helper() duplicates memory for the data given in const struct regulator_irq_desc *d - but it does not duplicate the irq name pointed from the given regulator_irq_desc. Nor does the request_threaded_irq(). I passed some of the IRQ names from the stack in the BD96801 driver ... a bug I should've caught earlier.

Well, good thing is that now I can fix the regulator_irq_helper() to do:

--- a/drivers/regulator/irq_helpers.c
+++ b/drivers/regulator/irq_helpers.c
@@ -352,6 +352,9 @@ void *regulator_irq_helper(struct device *dev,

h->irq = irq;
h->desc = *d;
+ h->desc.name = devm_kstrdup(dev, d->name, GFP_KERNEL);
+ if (!h->desc.name)
+ return ERR_PTR(-ENOMEM);

ret = init_rdev_state(dev, h, rdev, common_errs, per_rdev_errs,
rdev_amount);

I'll send a patch if this sounds like a correct thing to do.



--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~