From: Marc Zyngier <marc.zyngier@arm.com>
To: Brendan Higgins <brendanhiggins@google.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Wolfram Sang" <wsa@the-dreams.de>,
robh+dt@kernel.org, mark.rutland@arm.com, tglx@linutronix.de,
jason@lakedaemon.net, "Joel Stanley" <joel@jms.id.au>,
"Vladimir Zapolskiy" <vz@mleia.com>,
"Kachalov Anton" <mouse@mayc.ru>,
"Cédric Le Goater" <clg@kaod.org>,
linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
"OpenBMC Maillist" <openbmc@lists.ozlabs.org>
Subject: Re: [PATCH v6 2/5] irqchip/aspeed-i2c-ic: Add I2C IRQ controller for Aspeed
Date: Wed, 29 Mar 2017 11:55:17 +0100 [thread overview]
Message-ID: <75ef2cc1-44d7-0137-96e5-77ba68ee071f@arm.com> (raw)
In-Reply-To: <CAFd5g46TAGHWtH7p1o=AJqy8_SygpJZ4RJkJpUwDD3nKxpB5YQ@mail.gmail.com>
On 29/03/17 10:59, Brendan Higgins wrote:
> The main reason I took this approach is just because I thought it was
> cleaner from the perspective of the busses which are totally
> independent (except for the fact that they share a single hardware
> interrupt).
>
> I did not make any measurements, so I doubt that I have anything to
> add that you don't already know. I saw other usages of chained
> interrupts that do the same thing (scan a "status" register and use
> them to make software interrupts) and I thought that is basically what
> the dummy irq chip code is for. The only thing I thought I was doing
> that was novel was actually breaking out the dummy irqchip into its
> own driver; it is not my idea, but I do think makes it a lot cleaner.
> Nevertheless, it should be cheap in terms of number of instructions;
> the most expensive part looks like looking up the mapping. In any
> case, I think the low hanging fruit here is supporting buffering or
> DMA, like Ben suggested.
>
> To address the comment on being over engineered: outside of the init
> function (which would exist regardless of how we do this, if not here
> then in the I2C driver); the code is actually pretty small and
> generic.
>
> All that being said, it would not be very hard to do this without
> using the dummy irqchip code and it would definitely be smaller in
> terms of indirection and space used, but I think the code would
> actually be more complicated to read. We would be going back to having
> an I2C controller along with the I2C busses; where all the I2C
> controller does is read the IRQ register and then call the appropriate
> bus irq handler, which looks a lot like a dummy irqchip.
As long as you're happy with the performance and the restrictions that
come attached to the HW, I'm happy to take the irqchip patches.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2017-03-29 10:55 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-28 5:12 [PATCH v6 0/5] i2c: aspeed: added driver for Aspeed I2C Brendan Higgins
2017-03-28 5:12 ` [PATCH v6 1/5] irqchip/aspeed-i2c-ic: binding docs for Aspeed I2C Interrupt Controller Brendan Higgins
2017-03-28 8:49 ` Benjamin Herrenschmidt
2017-03-29 10:34 ` Brendan Higgins
2017-03-29 12:11 ` Benjamin Herrenschmidt
2017-03-29 20:51 ` Brendan Higgins
2017-03-29 21:17 ` Benjamin Herrenschmidt
2017-04-03 14:16 ` Rob Herring
2017-03-28 5:12 ` [PATCH v6 2/5] irqchip/aspeed-i2c-ic: Add I2C IRQ controller for Aspeed Brendan Higgins
2017-03-28 8:32 ` Marc Zyngier
2017-03-28 9:12 ` Benjamin Herrenschmidt
2017-03-28 9:40 ` Marc Zyngier
2017-03-28 20:50 ` Benjamin Herrenschmidt
2017-03-29 9:59 ` Brendan Higgins
2017-03-29 10:55 ` Marc Zyngier [this message]
2017-03-28 8:52 ` Benjamin Herrenschmidt
2017-03-29 10:58 ` Joel Stanley
2017-03-29 20:16 ` Brendan Higgins
2017-03-28 5:12 ` [PATCH v6 3/5] i2c: aspeed: added documentation for Aspeed I2C driver Brendan Higgins
2017-03-28 8:54 ` Benjamin Herrenschmidt
2017-03-29 10:25 ` Brendan Higgins
2017-04-03 14:22 ` Rob Herring
2017-04-03 14:24 ` Rob Herring
2017-03-28 5:12 ` [PATCH v6 4/5] i2c: aspeed: added driver for Aspeed I2C Brendan Higgins
2017-03-28 8:57 ` Benjamin Herrenschmidt
2017-03-28 9:09 ` Benjamin Herrenschmidt
2017-03-29 10:23 ` Brendan Higgins
2017-03-31 0:33 ` Joel Stanley
2017-03-31 7:33 ` Benjamin Herrenschmidt
2017-04-24 18:56 ` Brendan Higgins
2017-04-25 2:19 ` Benjamin Herrenschmidt
2017-04-25 8:32 ` Brendan Higgins
2017-04-25 8:50 ` Ryan Chen
2017-04-25 9:34 ` Benjamin Herrenschmidt
2017-04-25 9:47 ` Ryan Chen
2017-04-25 19:50 ` Brendan Higgins
2017-04-26 0:52 ` Ryan Chen
2017-03-28 5:12 ` [PATCH v6 5/5] i2c: aspeed: added slave support for Aspeed I2C driver Brendan Higgins
2017-03-31 0:01 ` [PATCH v6 0/5] i2c: aspeed: added driver for Aspeed I2C Andrew Jeffery
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