linux-kernel - Re: [PATCH 2/3] bus: ti-sysc: Fix timer handling with drop pm_runtime_irq

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Date:   Sat, 26 Jan 2019 20:31:51 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-omap <linux-omap@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Keerthy <j-keerthy@...com>,
        Ladislav Michl <ladis@...ux-mips.org>,
        Pavel Machek <pavel@....cz>,
        Sebastian Reichel <sre@...nel.org>,
        Tero Kristo <t-kristo@...com>,
        Thierry Reding <thierry.reding@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andreas Kemnade <andreas@...nade.info>
Subject: Re: [PATCH 2/3] bus: ti-sysc: Fix timer handling with drop pm_runtime_irq_safe()


> Am 26.01.2019 um 19:41 schrieb Andreas Kemnade <andreas@...nade.info>:
> 
> On Tue, 22 Jan 2019 09:57:16 -0800
> Tony Lindgren <tony@...mide.com> wrote:
> 
>> Commit 84badc5ec5fc ("ARM: dts: omap4: Move l4 child devices to probe
>> them with ti-sysc") started producing a warning for pwm-omap-dmtimer:
>> 
>> WARNING: CPU: 0 PID: 77 at drivers/bus/omap_l3_noc.c:147
>> l3_interrupt_handler+0x2f8/0x388
>> 44000000.ocp:L3 Custom Error: MASTER MPU TARGET L4PER2 (Idle):
>> Data Access in Supervisor mode during Functional access
>> ...
>> __pm_runtime_idle
>> omap_dm_timer_disable
>> pwm_omap_dmtimer_start
>> pwm_omap_dmtimer_enable
>> pwm_apply_state
>> pwm_vibrator_start
>> pwm_vibrator_play_work
>> 
>> This is because the timer that pwm-omap-dmtimer is using is now being
>> probed with ti-sysc interconnect target module instead of omap_device
>> and the ti-sysc quirk for SYSC_QUIRK_LEGACY_IDLE is not fully
>> compatible with what omap_device has been doing.
>> 
>> We could fix this by reverting the timer changes and have the timer
>> probe again with omap_device. Or we could add more quirk handling to
>> ti-sysc driver. But as these options don't work nicely as longer term
>> solutions, let's just make timers probe with ti-sysc without any
>> quirks.
>> 
>> To do this, all we need to do is remove quirks for timers for ti-sysc,
>> and drop the bogus pm_runtime_irq_safe() flag for timer-ti-dm.
>> 
>> We should not use pm_runtime_irq_safe() anyways for drivers as it will
>> take a permanent use count on the parent device blocking the parent
>> devices from idling and has been forcing ti-sysc driver to use a
>> quirk flag.
>> 
>> Note that we will move the timer data to DEBUG section later on in
>> clean-up patches.
>> 
> together with 1/3 it fixes things on pyra.
> 
> Tested-By: Andreas Kemnade <andreas@...nade.info>

H. Nikolaus Schaller <hns@...delico.com>