From: Brendan Higgins <brendanhiggins@google.com>
To: Joel Stanley <joel@jms.id.au>
Cc: linux@roeck-us.net,
"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"Andrew Jeffery" <andrew@aj.id.au>,
linux-i2c@vger.kernel.org,
"OpenBMC Maillist" <openbmc@lists.ozlabs.org>,
linux-aspeed@lists.ozlabs.org,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Cédric Le Goater" <clg@kaod.org>,
"Jae Hyun Yoo" <jae.hyun.yoo@linux.intel.com>
Subject: Re: [PATCH] i2c: aspeed: Acknowledge most interrupts early in interrupt handler
Date: Mon, 17 Sep 2018 18:28:32 -0700 [thread overview]
Message-ID: <CAFd5g44dZ+SvCBGNztuq2izMb7401izXVoq=fU9=BehrwikVwA@mail.gmail.com> (raw)
In-Reply-To: <CACPK8XchoryZ_RS8f4n=-GoT-Ak+dXuC3cgqLmxK9C=gySEJFQ@mail.gmail.com>
On Mon, Sep 17, 2018 at 6:11 PM Joel Stanley <joel@jms.id.au> wrote:
>
> On Fri, 14 Sep 2018 at 13:00, Guenter Roeck <linux@roeck-us.net> wrote:
> >
> > Commit 3e9efc3299dd ("i2c: aspeed: Handle master/slave combined irq events
> > properly") moved interrupt acknowledgment to the end of the interrupt
> > handler. In part this was done because the AST2500 datasheet says:
> >
> > I2CD10 Interrupt Status Register
> > bit 2 Receive Done Interrupt status
> > S/W needs to clear this status bit to allow next data receiving.
> >
> > Acknowledging Receive Done before receive data was handled resulted in
> > receive errors on high speed I2C busses.
> >
> > However, interrupt acknowledgment was not only moved to the end of the
> > interrupt handler for Receive Done Interrupt status, but for all interrupt
> > status bits. This could result in race conditions if a second interrupt was
> > received during interrupt handling and not handled but still acknowledged
> > at the end of the interrupt handler.
> >
> > Acknowledge only "Receive Done Interrupt status" late in the interrupt
> > handler to solve the problem.
> >
> > Fixes: 3e9efc3299dd ("i2c: aspeed: Handle master/slave combined irq events properly")
> > Cc: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> > Cc: Joel Stanley <joel@jms.id.au>
> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>
> Thanks for getting to the bottom of this Guenter. I gave it a spin on
> Romulus (ast2500) and Palmetto (ast2400) without issue.
>
> Tested-by: Joel Stanley <joel@jms.id.au>
>
Nice work! Thanks!
Acked-by: Brendan Higgins <brendanhiggins@google.com>
next prev parent reply other threads:[~2018-09-18 1:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 3:30 [PATCH] i2c: aspeed: Acknowledge most interrupts early in interrupt handler Guenter Roeck
2018-09-14 16:28 ` Jae Hyun Yoo
2018-09-17 16:34 ` Wolfram Sang
2018-09-17 17:16 ` Jae Hyun Yoo
2018-09-17 18:48 ` Guenter Roeck
2018-09-18 1:11 ` Joel Stanley
2018-09-18 1:28 ` Brendan Higgins [this message]
2018-09-24 21:45 ` Wolfram Sang
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