linux-kernel - Re: [PATCH 1/5] clocksource: mediatek: do not enable GPT_CLK

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Date:	Tue, 14 Jul 2015 15:39:47 +0800
From:	Daniel Kurtz <djkurtz@...omium.org>
To:	Yingjoe Chen <yingjoe.chen@...iatek.com>
Cc:	Matthias Brugger <matthias.bgg@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Michael Turquette <mturquette@...libre.com>,
	James Liao <jamesjj.liao@...iatek.com>,
	Russell King <linux@....linux.org.uk>,
	"open list:OPEN FIRMWARE AND..." <devicetree@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Catalin Marinas <catalin.marinas@....com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Rob Herring <robh+dt@...nel.org>,
	linux-mediatek@...ts.infradead.org,
	Sascha Hauer <kernel@...gutronix.de>,
	Olof Johansson <olof@...om.net>,
	srv_heupstream <srv_heupstream@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, linux-clk@...r.kernel.org
Subject: Re: [PATCH 1/5] clocksource: mediatek: do not enable GPT_CLK_EVT when setup

Hi Yingjoe,

On Mon, Jul 13, 2015 at 5:32 PM, Yingjoe Chen <yingjoe.chen@...iatek.com> wrote:
> Spurious mtk timer interrupt is noticed at boot and cause kernel
> crash. It seems if GPT is enabled, it will latch irq status even
> when its IRQ is disabled. When irq is enabled afterward, we see
> spurious interrupt.
> Change init flow to only enable GPT_CLK_SRC at mtk_timer_init.
>
> Signed-off-by: Yingjoe Chen <yingjoe.chen@...iatek.com>
> ---
>  drivers/clocksource/mtk_timer.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/clocksource/mtk_timer.c b/drivers/clocksource/mtk_timer.c
> index 68ab423..237c20b 100644
> --- a/drivers/clocksource/mtk_timer.c
> +++ b/drivers/clocksource/mtk_timer.c
> @@ -156,9 +156,11 @@ static void mtk_timer_global_reset(struct mtk_clock_event_device *evt)
>         writel(0x3f, evt->gpt_base + GPT_IRQ_ACK_REG);
>  }
>
> -static void
> -mtk_timer_setup(struct mtk_clock_event_device *evt, u8 timer, u8 option)
> +static void mtk_timer_setup(struct mtk_clock_event_device *evt, u8 timer,
> +                           u8 option, bool enable)

This function can be: __init

Other than this tiny nit, and the small potential conflict in patch 4,
this whole series is:

Reviewed-by: Daniel Kurtz <djkurtz@...omium.org>

(I do think it is a bit strange that the mediatek,mt6577-timer binding
does not use "clock-names", but that is independent of this patch
set).

Thanks!


>  {
> +       u32 val;
> +
>         writel(TIMER_CTRL_CLEAR | TIMER_CTRL_DISABLE,
>                 evt->gpt_base + TIMER_CTRL_REG(timer));
>
> @@ -167,8 +169,10 @@ mtk_timer_setup(struct mtk_clock_event_device *evt, u8 timer, u8 option)
>
>         writel(0x0, evt->gpt_base + TIMER_CMP_REG(timer));
>
> -       writel(TIMER_CTRL_OP(option) | TIMER_CTRL_ENABLE,
> -                       evt->gpt_base + TIMER_CTRL_REG(timer));
> +       val = TIMER_CTRL_OP(option);
> +       if (enable)
> +               val |= TIMER_CTRL_ENABLE;
> +       writel(val, evt->gpt_base + TIMER_CTRL_REG(timer));
>  }
>
>  static void mtk_timer_enable_irq(struct mtk_clock_event_device *evt, u8 timer)
> @@ -235,12 +239,12 @@ static void __init mtk_timer_init(struct device_node *node)
>         evt->ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
>
>         /* Configure clock source */
> -       mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN);
> +       mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN, true);
>         clocksource_mmio_init(evt->gpt_base + TIMER_CNT_REG(GPT_CLK_SRC),
>                         node->name, rate, 300, 32, clocksource_mmio_readl_up);
>
>         /* Configure clock event */
> -       mtk_timer_setup(evt, GPT_CLK_EVT, TIMER_CTRL_OP_REPEAT);
> +       mtk_timer_setup(evt, GPT_CLK_EVT, TIMER_CTRL_OP_REPEAT, false);
>         clockevents_config_and_register(&evt->dev, rate, 0x3,
>                                         0xffffffff);
>
> --
> 1.8.1.1.dirty
>
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