genirq/irqdomain: Allow partial trimming of irq_data hierarchy

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It appears that some HW is ugly enough that not all the interrupts
connected to a particular interrupt controller end up with the same
hierarchy depth (some of them are terminated early). This leaves
the irqchip hacker with only two choices, both equally bad:

- create discrete domain chains, one for each "hierarchy depth",
  which is very hard to maintain

- create fake hierarchy levels for the shallow paths, leading
  to all kind of problems (what are the safe hwirq values for these
  fake levels?)

Implement the ability to cut short a single interrupt hierarchy
from a level marked as being disconnected by using the new
irq_domain_disconnect_hierarchy() helper.

The irqdomain allocation code will then perform the trimming

Signed-off-by: Marc Zyngier <maz@kernel.org>

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This commit is contained in:

Marc Zyngier 2020-10-06 10:10:20 +01:00

parent f4d51dffc6

commit 5556797662

2 changed files with 98 additions and 4 deletions

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3

include/linux/irqdomain.h

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99

kernel/irq/irqdomain.c

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