Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Wed, 12 Jul 2017 10:00:55 +0200 | Subject | Re: [GIT pull] irq updates for 4.13 |
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Hi Grygorii,
On Tue, Jul 11, 2017 at 5:39 PM, Grygorii Strashko <grygorii.strashko@ti.com> wrote: > On 07/11/2017 09:41 AM, Thomas Gleixner wrote: >> On Tue, 11 Jul 2017, Tony Lindgren wrote: >>> * Thomas Gleixner <tglx@linutronix.de> [170711 02:48]: >>> And "external abort on non-linefetch" means something is not clocked >>> in this case. The following alone makes things boot for me again, but I don't >>> quite follow what has now changed with the ordering.. Thomas, any ideas? >> >> Ah. Now that makes sense. >> >> Unpatched the ordering is: >> >> chip_bus_lock(desc); >> irq_request_resources(desc); >> >> Now the offending change reordered the calls. OMAP gpio has: >> >> omap_gpio_irq_bus_lock() >> pm_runtime_get_sync(bank->chip.parent); >> >> So that at least explains the error. So that omap gpio irq chip (ab)uses >> the bus_lock() callback to do runtime power management. Sigh, I did not >> expect that. Let me have a deeper look if that's OMAP only or whether this >> happens in other places as well. > > It was the only one way to power on GPIO bank when the first GPIO IRQ is requested, > as all other irqchip callbacks are under raw_lock while pm_runtime uses spinlock, as > result on -RT it was not possible to use PM runtime in other irqchip callbacks. > > Now, I think, It might be possible to use irq_chip_pm_get(), but there is one problem - > OMAP Power management platform code can call omap2_gpio_prepare_for_idle()/omap2_gpio_resume_after_idle() > which expected to disable GPIO banks using PM runtime and current driver implementation > expect to have PM runtime usage_count = 1. > > Tony, Potentially we can use pm_runtime_force_suspend()/resume() there, but they are not compatible with > irqoff context (CPUIdle late stages). > > In other words, below patch should fix this issue, but will break CPUIdle on OMAP :( > > -- > From dfca1c806f03ad6bdd72b634d71c96d39bda2046 Mon Sep 17 00:00:00 2001 > From: Grygorii Strashko <grygorii.strashko@ti.com> > Date: Tue, 11 Jul 2017 10:36:23 -0500 > Subject: [PATCH] gpio: omap: switch to use irq_chip_pm_get/put() > > Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
That looks similar to how gpio-rcar was fixed, which used to do the same trick in its bus_lock() callbacks.
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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