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From: Anup Patel <anup@brainfault.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	palmer@sifive.com, jason@lakedaemon.net,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, aou@eecs.berkeley.edu,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	linux-riscv@lists.infradead.org, shorne@gmail.com,
	Palmer Dabbelt <palmer@dabbelt.com>
Subject: Re: [PATCH 3/6] irqchip: RISC-V Local Interrupt Controller Driver
Date: Thu, 26 Jul 2018 09:08:00 +0530	[thread overview]
Message-ID: <CAAhSdy31=D3jOgvrc+Td-TeKQMazPA-suFjOy9XwEuima1WdeA@mail.gmail.com> (raw)
In-Reply-To: <20180725112457.GA24502@lst.de>

On Wed, Jul 25, 2018 at 4:54 PM, Christoph Hellwig <hch@lst.de> wrote:
> On Wed, Jul 25, 2018 at 12:18:39PM +0100, Marc Zyngier wrote:
>> This feels odd. It means that you cannot have the following sequence:
>>
>>       local_irq_disable();
>>       enable_irq(x); // where x is owned by a remote hart
>>
>> as smp_call_function_single() requires interrupts to be enabled.
>>
>> More fundamentally, why are you trying to make these interrupts look
>> global while they aren't? arm/arm64 have similar restrictions with GICv2
>> and earlier, and treats these interrupts as per-cpu.
>>
>> Given that the drivers that deal with drivers connected to the per-hart
>> irqchip are themselves likely to be aware of the per-cpu aspect, it
>> would make sense to align things (we've been through that same
>> discussion about the clocksource driver a few weeks back).
>
> Right now the only direct consumers are said clocksource, the PLIC
> driver later in this series and the RISC-V arch IPI code.  None of them
> is going to do a manual enable_irq, so I guess the remote case of the
> code is simply dead code.  I'll take a look at converting them to
> per-cpu.  I guess the GICv2 driver is the best template?

Actually, RISCV HLIC and PLIC are very similar to RPi2 and RPi3 SOCs.

On RPi2 and RPi3, we have per-CPU BCM2836 local intc and the global
interrupts are managed using BCM2835 intc. You should certainly have
a look a this drivers because these very simple compared to GICv2 and
GICv3 drivers.

Regards,
Anup

  parent reply	other threads:[~2018-07-26  3:38 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-25  9:36 RISC-V irqchip drivers Christoph Hellwig
2018-07-25  9:36 ` [PATCH 1/6] RISC-V: simplify software interrupt / IPI code Christoph Hellwig
2018-07-25 21:44   ` Palmer Dabbelt
2018-07-26  8:10     ` Christoph Hellwig
2018-07-25  9:36 ` [PATCH 2/6] RISC-V: remove INTERRUPT_CAUSE_* defines from asm/irq.h Christoph Hellwig
2018-07-25 21:44   ` Palmer Dabbelt
2018-07-25  9:36 ` [PATCH 3/6] irqchip: RISC-V Local Interrupt Controller Driver Christoph Hellwig
2018-07-25 11:18   ` Marc Zyngier
2018-07-25 11:24     ` Christoph Hellwig
2018-07-25 11:37       ` Marc Zyngier
2018-07-25 17:54         ` Atish Patra
2018-07-26  3:38       ` Anup Patel [this message]
2018-07-26  8:27         ` Christoph Hellwig
2018-07-26 13:39           ` Anup Patel
2018-08-01 18:55       ` Thomas Gleixner
2018-08-02  7:34         ` Christoph Hellwig
2018-08-02  9:35           ` Thomas Gleixner
2018-08-02  9:43             ` Christoph Hellwig
2018-08-02  9:44               ` Thomas Gleixner
2018-08-04  4:03         ` Palmer Dabbelt
2018-08-04 16:40           ` Thomas Gleixner
2018-07-25  9:36 ` [PATCH 4/6] dt-bindings: interrupt-controller: RISC-V local interrupt controller docs Christoph Hellwig
2018-07-31 22:37   ` Rob Herring
2018-08-01  7:13     ` Christoph Hellwig
2018-08-01 18:14       ` Rob Herring
2018-07-25  9:36 ` [PATCH 5/6] irqchip: New RISC-V PLIC Driver Christoph Hellwig
2018-07-25  9:36 ` [PATCH 6/6] dt-bindings: interrupt-controller: RISC-V PLIC documentation Christoph Hellwig
2018-07-31 22:46   ` Rob Herring
2018-08-01  7:16     ` Christoph Hellwig
2018-08-01 18:26       ` Rob Herring
2018-08-02  9:55         ` Christoph Hellwig
2018-08-02 14:43           ` Rob Herring
2018-08-04  1:48         ` Palmer Dabbelt
2018-07-25 21:26 ` RISC-V irqchip drivers Palmer Dabbelt

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