On 2024-11-19 11:49 AM, Rob Herring wrote: > On Tue, Nov 19, 2024 at 10:47 AM Samuel Holland > <samuel.holland@xxxxxxxxxx> wrote: >> >> Hi Rob, >> >> On 2024-11-19 9:41 AM, Rob Herring wrote: >>> On Thu, Nov 14, 2024 at 11:56:49AM -0800, Samuel Holland wrote: >>>> commit 7f00be96f125 ("of: property: Add device link support for >>>> interrupt-parent, dmas and -gpio(s)") started adding device links for >>>> the interrupt-parent property. Later, commit f265f06af194 ("of: >>>> property: Fix fw_devlink handling of interrupts/interrupts-extended") >>>> added full support for parsing the interrupts and interrupts-extended >>>> properties, which includes looking up the node of the parent domain. >>>> This made the handler for the interrupt-parent property redundant. >>>> >>>> In fact, creating device links based solely on interrupt-parent is >>>> problematic, because it can create spurious cycles. A node may have >>>> this property without itself being an interrupt controller or consumer. >>>> For example, this property is often present in the root node or a /soc >>>> bus node to set the default interrupt parent for child nodes. However, >>>> it is incorrect for the bus to depend on the interrupt controller, as >>>> some of the bus's childre may not be interrupt consumers at all or may >>> >>> typo >>> >>>> have a different interrupt parent. >>>> >>>> Resolving these spurious dependency cycles can cause an incorrect probe >>>> order for interrupt controller drivers. This was observed on a RISC-V >>>> system with both an APLIC and IMSIC under /soc, where interrupt-parent >>>> in /soc points to the APLIC, and the APLIC msi-parent points to the >>>> IMSIC. fw_devlink found three dependency cycles and attempted to probe >>>> the APLIC before the IMSIC. After applying this patch, there were no >>>> dependency cycles and the probe order was correct. >>>> >>>> Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx> >>> >>> I assume this should go to stable? It needs Fixes tags. >> >> What commit should I put in the Fixes tag? f265f06af194 ("of: property: Fix >> fw_devlink handling of interrupts/interrupts-extended"), because it finished >> making this code redundant? That commit didn't introduce any new bugs--this code >> was always wrong--but I would be hesitant to backport this change any further, >> because it might cause regressions without the "interrupts" property parsing in >> place. > > I'd guess that f265f06af194 has been backported to everything with > 7f00be96f125. I think we want either all 3 commits or none of them. If > something only works with a subset, then upstream is broken. Of the current LTS branches, v5.10 has only 7f00be96f125. f265f06af194 was only backported as far as v5.15, since it Fixes: 4104ca776ba3 ("of: property: Add fw_devlink support for interrupts"), which was merged for v5.12. I will add this same Fixes: tag for v2. Regards, Samuel