Date: Tue, 9 Apr 2024 15:56:22 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: linux-sh@...r.kernel.org, Damien Le Moal <dlemoal@...nel.org>, 
	Niklas Cassel <cassel@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Thomas Gleixner <tglx@...utronix.de>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Krzysztof Wilczyński <kw@...ux.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Magnus Damm <magnus.damm@...il.com>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	Rich Felker <dalias@...c.org>, John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>, 
	Lee Jones <lee@...nel.org>, Helge Deller <deller@....de>, 
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	Sebastian Reichel <sre@...nel.org>, Chris Morgan <macromorgan@...mail.com>, 
	Linus Walleij <linus.walleij@...aro.org>, Arnd Bergmann <arnd@...db.de>, 
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	Andrew Morton <akpm@...ux-foundation.org>, Guenter Roeck <linux@...ck-us.net>, 
	Kefeng Wang <wangkefeng.wang@...wei.com>, Stephen Rothwell <sfr@...b.auug.org.au>, 
	Javier Martinez Canillas <javierm@...hat.com>, Guo Ren <guoren@...nel.org>, 
	Azeem Shaikh <azeemshaikh38@...il.com>, Max Filippov <jcmvbkbc@...il.com>, 
	Jonathan Corbet <corbet@....net>, Jacky Huang <ychuang3@...oton.com>, 
	Herve Codina <herve.codina@...tlin.com>, 
	Manikanta Guntupalli <manikanta.guntupalli@....com>, Anup Patel <apatel@...tanamicro.com>, 
	Biju Das <biju.das.jz@...renesas.com>, 
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>, 
	Sam Ravnborg <sam@...nborg.org>, Sergey Shtylyov <s.shtylyov@....ru>, 
	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, linux-ide@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, linux-pci@...r.kernel.org, 
	linux-serial@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [RESEND v7 08/37] clocksource: sh_tmu: CLOCKSOURCE support.

Hi Sato-san,

On Thu, Apr 4, 2024 at 7:15 AM Yoshinori Sato
<ysato@...rs.sourceforge.jp> wrote:
> Allows initialization as CLOCKSOURCE.
>
> Signed-off-by: Yoshinori Sato <ysato@...rs.sourceforge.jp>

Thanks for your patch!

> --- a/drivers/clocksource/sh_tmu.c
> +++ b/drivers/clocksource/sh_tmu.c

> @@ -495,7 +514,12 @@ static int sh_tmu_map_memory(struct sh_tmu_device *tmu)
>
>  static int sh_tmu_parse_dt(struct sh_tmu_device *tmu)
>  {
> -       struct device_node *np = tmu->pdev->dev.of_node;
> +       struct device_node *np;

Technically, np might be used uninitialized.

> +
> +       if (tmu->pdev)
> +               np = tmu->pdev->dev.of_node;

If you would set up tmu->np in sh_tmu_setup_pdev()...

> +       if (tmu->np)
> +               np = tmu->np;

.. you could just assign np = tmu->np unconditionally.

>
>         tmu->model = SH_TMU;
>         tmu->num_channels = 3;

> @@ -665,6 +734,7 @@ static void __exit sh_tmu_exit(void)
>         platform_driver_unregister(&sh_tmu_device_driver);
>  }
>
> +TIMER_OF_DECLARE(sh_tmu, "renesas,tmu", sh_tmu_of_register);

As there are now two entry points, the device is actually probed twice:
once from TIMER_OF_DECLARE/sh_tmu_of_register(), and a second
time from platform_driver/sh_tmu_probe().

E.g. on Armadillo-800-EVA with R-Mobile A1 (booting Linux on ARM
(not SH), and using TMU as the main clock source):

    timer@...80000 ch0: used for clock events
    timer@...80000 ch0: used for periodic clock events
    timer@...80000 ch1: used as clock source
    clocksource: timer@...80000: mask: 0xffffffff max_cycles:
0xffffffff, max_idle_ns: 154445288668 ns
    ...
    fff80000.timer ch0: used for clock events
    genirq: Flags mismatch irq 16. 00015a04 (fff80000.timer) vs.
00015a04 (timer@...80000)
    fff80000.timer ch0: failed to request irq 16
    fff80000.timer ch1: used as clock source
    clocksource: fff80000.timer: mask: 0xffffffff max_cycles:
0xffffffff, max_idle_ns: 154445288668 ns

After this, the timer seems to be stuck, and the boot is blocked.

On Marzen with R-Car H1 (booting Linux on ARM (not SH), and using
arm_global_timer as the main clock source), I also see the double
timer probe, but no such lock-up.  I expect you to see the double
timer probe on SH775x, too?

The double probe can be fixed by adding a call to
of_node_set_flag(np, OF_POPULATED) at the end of sh_tmu_of_register()
in case of success, cfr. [1].

I haven't found the cause of the stuck timer on R-Mobile A1 yet;
both the TMU clock and the A4R power domain seem to be activated...

>  #ifdef CONFIG_SUPERH
>  sh_early_platform_init("earlytimer", &sh_tmu_device_driver);
>  #endif

[1] "[PATCH] clocksource/drivers/renesas-ostm: Avoid reprobe after
successful early probe"
    https://lore.kernel.org/all/bd027379713cbaafa21ffe9e848ebb7f475ca0e7.1710930542.git.geert+renesas@glider.be/

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg

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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