Re: [PATCH v1] Input: tegra-kbc - fix wakeup from suspend.

[Dmitry Torokhov]

Hi Rakesh,

On Thu, Aug 25, 2011 at 05:29:47PM -0700, riyer@xxxxxxxxxx wrote:
> From: Rakesh Iyer <riyer@xxxxxxxxxx>
> 
> For wakeup to be reliable, kbc needs to be in interrupt mode before suspend.
> Created common routine to control the FIFO interrupt.
> Added synchronization to ensure orderly suspend.
> 
> Signed-off-by: Rakesh Iyer <riyer@xxxxxxxxxx>
> ---
>  drivers/input/keyboard/tegra-kbc.c |   83 +++++++++++++++++++++++++++++-------
>  1 files changed, 67 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/input/keyboard/tegra-kbc.c b/drivers/input/keyboard/tegra-kbc.c
> index a5a7791..41de11f 100644
> --- a/drivers/input/keyboard/tegra-kbc.c
> +++ b/drivers/input/keyboard/tegra-kbc.c
> @@ -38,7 +38,7 @@
>  #define KBC_ROW_SCAN_DLY	5
>  
>  /* KBC uses a 32KHz clock so a cycle = 1/32Khz */
> -#define KBC_CYCLE_MS	32
> +#define KBC_CYCLES_PER_MS	32

This seems to be an unrelated change, can it be split out?

>  
>  /* KBC Registers */
>  
> @@ -55,6 +55,7 @@
>  
>  #define KBC_ROW_CFG0_0	0x8
>  #define KBC_COL_CFG0_0	0x18
> +#define KBC_TO_CNT_0	0x24
>  #define KBC_INIT_DLY_0	0x28
>  #define KBC_RPT_DLY_0	0x2c
>  #define KBC_KP_ENT0_0	0x30
> @@ -70,8 +71,10 @@ struct tegra_kbc {
>  	spinlock_t lock;
>  	unsigned int repoll_dly;
>  	unsigned long cp_dly_jiffies;
> +	unsigned int cp_to_wkup_dly;
>  	bool use_fn_map;
>  	bool use_ghost_filter;
> +	bool in_suspend;
>  	const struct tegra_kbc_platform_data *pdata;
>  	unsigned short keycode[KBC_MAX_KEY * 2];
>  	unsigned short current_keys[KBC_MAX_KPENT];
> @@ -341,6 +344,18 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
>  	kbc->num_pressed_keys = num_down;
>  }
>  
> +static void tegra_kbc_set_fifo_interrupt(struct tegra_kbc *kbc, bool enable)
> +{
> +	u32 val;
> +
> +	val = readl(kbc->mmio + KBC_CONTROL_0);
> +	if (enable)
> +		val |= KBC_CONTROL_FIFO_CNT_INT_EN;
> +	else
> +		val &= ~KBC_CONTROL_FIFO_CNT_INT_EN;
> +	writel(val, kbc->mmio + KBC_CONTROL_0);
> +}
> +
>  static void tegra_kbc_keypress_timer(unsigned long data)
>  {
>  	struct tegra_kbc *kbc = (struct tegra_kbc *)data;
> @@ -348,6 +363,14 @@ static void tegra_kbc_keypress_timer(unsigned long data)
>  	u32 val;
>  	unsigned int i;
>  
> +	/* Exit immediately if driver is trying to enter suspend. */
> +	spin_lock_irqsave(&kbc->lock, flags);
> +	if (kbc->in_suspend) {
> +		tegra_kbc_set_fifo_interrupt(kbc, true);
> +		spin_unlock_irqrestore(&kbc->lock, flags);
> +		return;
> +	}
> +	spin_unlock_irqrestore(&kbc->lock, flags);
>  	val = (readl(kbc->mmio + KBC_INT_0) >> 4) & 0xf;
>  	if (val) {
>  		unsigned long dly;
> @@ -370,9 +393,7 @@ static void tegra_kbc_keypress_timer(unsigned long data)
>  
>  		/* All keys are released so enable the keypress interrupt */
>  		spin_lock_irqsave(&kbc->lock, flags);
> -		val = readl(kbc->mmio + KBC_CONTROL_0);
> -		val |= KBC_CONTROL_FIFO_CNT_INT_EN;
> -		writel(val, kbc->mmio + KBC_CONTROL_0);
> +		tegra_kbc_set_fifo_interrupt(kbc, true);
>  		spin_unlock_irqrestore(&kbc->lock, flags);
>  	}
>  }
> @@ -380,15 +401,14 @@ static void tegra_kbc_keypress_timer(unsigned long data)
>  static irqreturn_t tegra_kbc_isr(int irq, void *args)
>  {
>  	struct tegra_kbc *kbc = args;
> -	u32 val, ctl;
> +	unsigned long flags;
> +	u32 val;
>  
>  	/*
>  	 * Until all keys are released, defer further processing to
>  	 * the polling loop in tegra_kbc_keypress_timer
>  	 */
> -	ctl = readl(kbc->mmio + KBC_CONTROL_0);
> -	ctl &= ~KBC_CONTROL_FIFO_CNT_INT_EN;
> -	writel(ctl, kbc->mmio + KBC_CONTROL_0);
> +	tegra_kbc_set_fifo_interrupt(kbc, false);
>  
>  	/*
>  	 * Quickly bail out & reenable interrupts if the fifo threshold
> @@ -397,16 +417,18 @@ static irqreturn_t tegra_kbc_isr(int irq, void *args)
>  	val = readl(kbc->mmio + KBC_INT_0);
>  	writel(val, kbc->mmio + KBC_INT_0);
>  
> -	if (val & KBC_INT_FIFO_CNT_INT_STATUS) {
> +	/* Exit immediately if driver is trying to enter suspend. */
> +	spin_lock_irqsave(&kbc->lock, flags);
> +	if (!kbc->in_suspend && (val & KBC_INT_FIFO_CNT_INT_STATUS))
>  		/*
>  		 * Schedule timer to run when hardware is in continuous
>  		 * polling mode.
>  		 */
>  		mod_timer(&kbc->timer, jiffies + kbc->cp_dly_jiffies);
> -	} else {
> -		ctl |= KBC_CONTROL_FIFO_CNT_INT_EN;
> -		writel(ctl, kbc->mmio + KBC_CONTROL_0);
> -	}
> +	else
> +		tegra_kbc_set_fifo_interrupt(kbc, true);
> +
> +	spin_unlock_irqrestore(&kbc->lock, flags);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -648,7 +670,7 @@ static int __devinit tegra_kbc_probe(struct platform_device *pdev)
>  	debounce_cnt = min(pdata->debounce_cnt, KBC_MAX_DEBOUNCE_CNT);
>  	scan_time_rows = (KBC_ROW_SCAN_TIME + debounce_cnt) * num_rows;
>  	kbc->repoll_dly = KBC_ROW_SCAN_DLY + scan_time_rows + pdata->repeat_cnt;
> -	kbc->repoll_dly = DIV_ROUND_UP(kbc->repoll_dly, KBC_CYCLE_MS);
> +	kbc->repoll_dly = DIV_ROUND_UP(kbc->repoll_dly, KBC_CYCLES_PER_MS);
>  
>  	input_dev->name = pdev->name;
>  	input_dev->id.bustype = BUS_HOST;
> @@ -735,10 +757,29 @@ static int tegra_kbc_suspend(struct device *dev)
>  	struct tegra_kbc *kbc = platform_get_drvdata(pdev);
>  
>  	if (device_may_wakeup(&pdev->dev)) {
> -		tegra_kbc_setup_wakekeys(kbc, true);
> -		enable_irq_wake(kbc->irq);
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&kbc->lock, flags);
> +		kbc->in_suspend = 1;
> +		spin_unlock_irqrestore(&kbc->lock, flags);
> +
> +		del_timer(&kbc->timer);

I'd expect this to be del_timer_sync().

Overall I think this is quite complex, do we really need to keep
interrupts enabled (as in enable_irq) for wakeup to work? It is my
understanding that wakeup (enable_irq_wake/disable_irq_wake) control is
separate from enable_irq/disable_irq control. If you can do
disable_irq() while system goes to sleep then the code will be much
simpler.

Thanks.

-- 
Dmitry
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