linux-kernel - [PATCH v3 0/2] irqchip: RISC-V PLIC cleanup and optimization

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Date:   Fri,  1 Jul 2022 15:24:38 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>
Cc:     Samuel Holland <samuel@...lland.org>, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: [PATCH v3 0/2] irqchip: RISC-V PLIC cleanup and optimization

This series removes the spinlocks and cpumask operations from the PLIC
driver's hot path. As far as I know, using the priority to mask
interrupts is an intended usage and will work on all existing
implementations. See [1] for more discussion.

This series depends on my other series[2] making the IRQ affinity mask
behavior more consistent between uniprocessor and SMP configurations.
(The Allwinner D1 is a uniprocessor SoC containing a PLIC.)

A further optimization is to take advantage of the fact that multiple
IRQs can be claimed at once. This allows removing the mask operations
for oneshot IRQs -- i.e. the combination of IRQCHIP_ONESHOT_SAFE and
IRQCHIP_EOI_THREADED, which is not currently supported. I will send
this as a separate series, since it makes more invasive changes to the
generic IRQ code.

[1]: https://lore.kernel.org/lkml/2b063917-17c8-0add-fadf-5aa42532fbbf@sholland.org/
[2]: https://lore.kernel.org/lkml/20220701200056.46555-1-samuel@sholland.org/

Changes in v3:
 - Rebased on top of irqchip-next
 - Split affinity series and PLIC series

Samuel Holland (2):
  irqchip/sifive-plic: Make better use of the effective affinity mask
  irqchip/sifive-plic: Separate the enable and mask operations

 drivers/irqchip/Kconfig           |  1 +
 drivers/irqchip/irq-sifive-plic.c | 64 ++++++++++++++++---------------
 2 files changed, 35 insertions(+), 30 deletions(-)

-- 
2.35.1