Re: Fix preempt-rt on AT91

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: Fix preempt-rt on AT91
Date	2016-03-08 12:30 +0100
Message-ID	<ranZT-8V-1@gated-at.bofh.it> (permalink)
References	<qRLgl-4Dy-5@gated-at.bofh.it> <qSm6g-3ZZ-47@gated-at.bofh.it> <r9iIW-5vt-5@gated-at.bofh.it> <ranGx-8tF-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Tue, 8 Mar 2016, Sebastian Andrzej Siewior wrote:
> I sucked this in. It seems to work. What remains that free_irq() thingy:
> |WARNING: CPU: 0 PID: 0 at kernel/irq/manage.c:1541 __free_irq+0xb4/0x2e0()
> |Trying to free already-free IRQ 16
> |CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.4-rt10+ #219
> |Hardware name: Atmel SAMA5
> |[<c0015bd0>] (unwind_backtrace) from [<c0013604>] (show_stack+0x10/0x14)
> |[<c0013604>] (show_stack) from [<c002b850>] (warn_slowpath_common+0x80/0xac)
> |[<c002b850>] (warn_slowpath_common) from [<c002b8ac>] (warn_slowpath_fmt+0x30/0x40)
> |[<c002b8ac>] (warn_slowpath_fmt) from [<c005adfc>] (__free_irq+0xb4/0x2e0)
> |[<c005adfc>] (__free_irq) from [<c005b0a0>] (free_irq+0x30/0x4c)
> |[<c005b0a0>] (free_irq) from [<c0429034>] (pit_clkevt_shutdown+0x24/0x2c)
> |[<c0429034>] (pit_clkevt_shutdown) from [<c0076430>] (clockevents_switch_state+0x60/0x130)
> |---[ end trace 0000000000000001 ]---
> 
> which is a different problem and was there. The new thing is this:

I think we really need to have this irq_en/disable_action() thingy sooner than
later.

> Is it possible to drop this disable/enable clock on the switch from pit
> to one shot mode?

There was an earlier discussion about the clk stuff. Actually the lock
protecting disable/enable should be made raw, but there was some crap going on
in some of the clk callbacks which made that impossible. We realy should
revisit this.

Thanks,

	tglx

Thread

Re: Fix preempt-rt on AT91 Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2016-03-05 12:40 +0100
  Re: Fix preempt-rt on AT91 Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-03-08 12:10 +0100
    Re: Fix preempt-rt on AT91 Thomas Gleixner <tglx@linutronix.de> - 2016-03-08 12:30 +0100
    Re: Fix preempt-rt on AT91 Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2016-03-08 19:40 +0100
      arm: at91: do not disable/enable clocks in a row Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-03-09 11:00 +0100

csiph-web