From: alexandre.belloni@free-electrons•com (Alexandre Belloni)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4.4-rt2] fix arm-at91-pit-remove-irq-handler-when-clock-is-unused.patch
Date: Thu, 17 Mar 2016 20:55:09 +0100 [thread overview]
Message-ID: <20160317195509.GF2831@piout.net> (raw)
In-Reply-To: <alpine.DEB.2.11.1601201158280.3575@nanos>
Hi Thomas,
On 20/01/2016 at 12:07:30 +0100, Thomas Gleixner wrote :
> Well freeing the irq from that context in RT only works because its called
> before SYSTEM_STATE=RUNNING. So no, this was wrong forever.
>
> The issue we are dealing with is that the timer interrupt is shared with the
> uart. So the timer has IRQ_NO_THREAD set and the uart interrupt gets force
> threaded. So that results in a failure to request the interrupt for the
> UART. That's not RT specific, that already happens in mainline if you add
> 'threadirqs' to the command line.
>
> So until the DT folks come to senses and we get that dummy demux chip done, I
> came up with the following - completely untested - solution.
>
> The downside of this is, that the timer will be delayed until the uart thread
> returns, but with the replacement clockevent in place on RT that's a non
> issue. For mainline it's obviously better than what we have now.
>
I've tested it and it seems to work properly on the few platform where I
can reproduce the issue. What is your plan regarding upstreaming? I
guess you can split and take the resulting patches through your tree.
--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2016-03-17 19:55 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-17 2:23 Fix preempt-rt on AT91 Alexandre Belloni
2016-01-17 2:23 ` [PATCH 4.4-rt2] fix arm-at91-pit-remove-irq-handler-when-clock-is-unused.patch Alexandre Belloni
2016-01-18 17:25 ` Sebastian Andrzej Siewior
2016-01-18 18:42 ` Alexandre Belloni
2016-01-18 20:24 ` Sebastian Andrzej Siewior
2016-01-19 1:22 ` Alexandre Belloni
2016-01-20 11:07 ` Thomas Gleixner
2016-03-17 19:55 ` Alexandre Belloni [this message]
2016-01-18 17:42 ` Fix preempt-rt on AT91 Sebastian Andrzej Siewior
2016-01-18 19:23 ` Alexandre Belloni
2016-01-18 20:30 ` Sebastian Andrzej Siewior
2016-01-19 1:02 ` Alexandre Belloni
2016-03-05 11:35 ` Alexandre Belloni
2016-03-08 11:06 ` Sebastian Andrzej Siewior
2016-03-08 11:26 ` Thomas Gleixner
2016-03-08 18:39 ` Alexandre Belloni
[not found] ` <20160309095824.GC10517@linutronix.de>
2016-03-17 18:09 ` arm: at91: do not disable/enable clocks in a row Alexandre Belloni
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