RE: [PATCH] arm64: dts: renesas: r8a7796: Add CMT device nodes

From: Biju Das <biju.das@bp.renesas.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Simon Horman <horms@verge.net.au>,
	Magnus Damm <magnus.damm@gmail.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <john.stultz@linaro.org>,
	Fabrizio Castro <fabrizio.castro@bp.renesas.com>,
	Samuel Holland <samuel@sholland.org>
Subject: RE: [PATCH] arm64: dts: renesas: r8a7796: Add CMT device nodes
Date: Fri, 25 Jan 2019 11:30:29 +0000	[thread overview]
Message-ID: <OSBPR01MB21034B1D07C9BA05859AEA73B89B0@OSBPR01MB2103.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <CAMuHMdW-qt+3iNit1wVxN2JyRwCArJzBNvvjDZJyxYRjvDkLuA@mail.gmail.com>

Hi Geert,

Thanks for the feedback. I started testing CMT on latest kernel(Linux-next-20190125 and also renesas-dev) and found that it is broken on R-Car M3-W device.

On further investigation the patch (" 8234f6734c5d74ac794e5517437f51c57d65f865"   PM-runtime: Switch autosuspend over to using hrtimers)  is causing the issue.

During clock source switching, It calls the function "sh_cmt_enable"  which calls " pm_runtime_get_sync(&ch->cmt->pdev->dev);"  and after that console freezes.

Sergei: Have you noticed this issue  on R-Car V3M and V3H boards with latest kernel?

Regards,
Biju

> -----Original Message-----
> From: linux-renesas-soc-owner@vger.kernel.org <linux-renesas-soc-
> owner@vger.kernel.org> On Behalf Of Geert Uytterhoeven
> Sent: 24 January 2019 10:16
> To: Biju Das <biju.das@bp.renesas.com>
> Cc: Rob Herring <robh+dt@kernel.org>; Mark Rutland
> <mark.rutland@arm.com>; Simon Horman <horms@verge.net.au>; Magnus
> Damm <magnus.damm@gmail.com>; Linux-Renesas <linux-renesas-
> soc@vger.kernel.org>; open list:OPEN FIRMWARE AND FLATTENED DEVICE
> TREE BINDINGS <devicetree@vger.kernel.org>; Geert Uytterhoeven
> <geert+renesas@glider.be>; Chris Paterson
> <Chris.Paterson2@renesas.com>; Daniel Lezcano
> <daniel.lezcano@linaro.org>; Thomas Gleixner <tglx@linutronix.de>; John
> Stultz <john.stultz@linaro.org>; Fabrizio Castro
> <fabrizio.castro@bp.renesas.com>; Samuel Holland <samuel@sholland.org>
> Subject: Re: [PATCH] arm64: dts: renesas: r8a7796: Add CMT device nodes
>
> Hi Biju,
>
> On Fri, Oct 26, 2018 at 10:32 AM Biju Das <biju.das@bp.renesas.com> wrote:
> > This patch adds CMT{0|1|2|3} device nodes for r8a7796 SoC.
> >
> > Signed-off-by: Biju Das <biju.das@bp.renesas.com>
> > ---
> > This patch is tested against renesas-dev
> >
> > I have executed on inconsistency-check, nanosleep and
> > clocksource_switch selftests on this arm64 SoC. The
> > inconsistency-check and nanosleep tests are working fine.The
> > clocksource_switch asynchronous test is failing due to inconsistency-check
> failure on "arch_sys_counter".
> >
> > But if i skip the clocksource_switching of "arch_sys_counter", the
> > asynchronous test is passing for CMT0/1/2/3 timer.
> >
> > Has any one noticed this issue?
>
> clockevents/next now has commit 7cd6dca3600d8d71
> ("clocksource/drivers/arch_timer: Workaround for Allwinner A64 timer
> instability").  Perhaps this is related, and the same test program may indicate
> similar issues?
>
> See also https://lore.kernel.org/lkml/20190113021719.46457-2-
> samuel@sholland.org/
>
> 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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