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

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Message-ID: <20190126194145.2b3484da@aktux>
Date:   Sat, 26 Jan 2019 19:41:45 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Tony Lindgren <tony@...mide.com>
Cc:     linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "H . Nikolaus Schaller" <hns@...delico.com>,
        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>
Subject: Re: [PATCH 2/3] bus: ti-sysc: Fix timer handling with drop
 pm_runtime_irq_safe()

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>

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