linux-kernel - Re: [PATCH v2 0/2] clocksource/drivers/sh

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Message-ID: <8917db78-fe40-487a-9ad5-f1bddfe0120c@linaro.org>
Date: Wed, 17 Sep 2025 11:02:45 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Niklas Söderlund
 <niklas.soderlund+renesas@...natech.se>, Thomas Gleixner
 <tglx@...utronix.de>, Geert Uytterhoeven <geert@...ux-m68k.org>,
 linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v2 0/2] clocksource/drivers/sh_cmt: Improve clock event
 design

On 10/09/2025 16:26, Niklas Söderlund wrote:
> Hello,
> 
> This series tries to address an issue with the Renesas CMT driver
> design. The driver do PM and clock handling in struct clock_event_device
> callbacks. This leads to LOCKDEP warnings and I think hints at a larger
> issue.
> 
>      =============================
>      [ BUG: Invalid wait context ]
>      6.17.0-rc3-arm64-renesas-03071-gb3c4f4122b28-dirty #21 Not tainted
>      -----------------------------
>      swapper/1/0 is trying to lock:
>      ffff00000898d180 (&dev->power.lock){-...}-{3:3}, at: __pm_runtime_resume+0x38/0x88
>      ccree e6601000.crypto: ARM CryptoCell 630P Driver: HW version 0xAF400001/0xDCC63000, Driver version 5.0
>      other info that might help us debug this:
>      ccree e6601000.crypto: ARM ccree device initialized
>      context-{5:5}
>      2 locks held by swapper/1/0:
>       #0: ffff80008173c298 (tick_broadcast_lock){-...}-{2:2}, at: __tick_broadcast_oneshot_control+0xa4/0x3a8
>       #1: ffff0000089a5858 (&ch->lock){....}-{2:2}
>      usbcore: registered new interface driver usbhid
>      , at: sh_cmt_start+0x30/0x364
>      stack backtrace:
>      CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.17.0-rc3-arm64-renesas-03071-gb3c4f4122b28-dirty #21 PREEMPT
>      Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
>      Call trace:
>       show_stack+0x14/0x1c (C)
>       dump_stack_lvl+0x6c/0x90
>       dump_stack+0x14/0x1c
>       __lock_acquire+0x904/0x1584
>       lock_acquire+0x220/0x34c
>       _raw_spin_lock_irqsave+0x58/0x80
>       __pm_runtime_resume+0x38/0x88
>       sh_cmt_start+0x54/0x364
>       sh_cmt_clock_event_set_oneshot+0x64/0xb8
>       clockevents_switch_state+0xfc/0x13c
>       tick_broadcast_set_event+0x30/0xa4
>       __tick_broadcast_oneshot_control+0x1e0/0x3a8
>       tick_broadcast_oneshot_control+0x30/0x40
>       cpuidle_enter_state+0x40c/0x680
>       cpuidle_enter+0x30/0x40
>       do_idle+0x1f4/0x26c
>       cpu_startup_entry+0x34/0x40
>       secondary_start_kernel+0x11c/0x13c
>       __secondary_switched+0x74/0x78
> 
> This series tries to address this by instead doing PM and clock
> management at probe time, and leaving them on for the CMT channels that
> are used as clock events. The CMT design is a bit messy as channels can
> be used both as clock sources and events. And the design to do the
> housekeeping for clock sources seems to be valid and is kept.
> 
> The work is tested on R-Car M3-N and R-Mobile A1.
> 
> See individual patches for change long.

Applied, thanks

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