Messages in this thread | | | From | Brendan Higgins <> | Date | Mon, 17 Sep 2018 18:28:32 -0700 | Subject | Re: [PATCH] i2c: aspeed: Acknowledge most interrupts early in interrupt handler |
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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>
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