Re: [PATCH] irqchip/irq-imx-irqsteer: Get/put PM runtime in ->irq_unmask()/irq_mask()

From: Lucas Stach
Date: Wed Jun 08 2022 - 06:57:00 EST


Am Mittwoch, dem 08.06.2022 um 18:50 +0800 schrieb Liu Ying:
> Now that runtime PM support was added in this driver, we have
> to enable power before accessing irqchip registers. And, after
> the access is done, we should disable power. This patch calls
> pm_runtime_get_sync() in ->irq_unmask() and pm_runtime_put() in
> ->irq_mask() to make sure power is managed for the register access.
>
Can you tell me in which case this is necessary? IIRC the IRQ core
already keeps the chip runtime resumed as soon as a IRQ is requested,
so why would it be in runtime suspend at mask/unmask?

Regards,
Lucas

> Fixes: 4730d2233311 ("irqchip/imx-irqsteer: Add runtime PM support")
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Cc: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> Cc: Fabio Estevam <festevam@xxxxxxxxx>
> Cc: NXP Linux Team <linux-imx@xxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> ---
> drivers/irqchip/irq-imx-irqsteer.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/irqchip/irq-imx-irqsteer.c b/drivers/irqchip/irq-imx-irqsteer.c
> index 96230a04ec23..a5eabe71e8ab 100644
> --- a/drivers/irqchip/irq-imx-irqsteer.c
> +++ b/drivers/irqchip/irq-imx-irqsteer.c
> @@ -45,11 +45,14 @@ static int imx_irqsteer_get_reg_index(struct irqsteer_data *data,
>
> static void imx_irqsteer_irq_unmask(struct irq_data *d)
> {
> + struct device *dev = d->domain->dev;
> struct irqsteer_data *data = d->chip_data;
> int idx = imx_irqsteer_get_reg_index(data, d->hwirq);
> unsigned long flags;
> u32 val;
>
> + pm_runtime_get_sync(dev);
> +
> raw_spin_lock_irqsave(&data->lock, flags);
> val = readl_relaxed(data->regs + CHANMASK(idx, data->reg_num));
> val |= BIT(d->hwirq % 32);
> @@ -59,6 +62,7 @@ static void imx_irqsteer_irq_unmask(struct irq_data *d)
>
> static void imx_irqsteer_irq_mask(struct irq_data *d)
> {
> + struct device *dev = d->domain->dev;
> struct irqsteer_data *data = d->chip_data;
> int idx = imx_irqsteer_get_reg_index(data, d->hwirq);
> unsigned long flags;
> @@ -69,6 +73,8 @@ static void imx_irqsteer_irq_mask(struct irq_data *d)
> val &= ~BIT(d->hwirq % 32);
> writel_relaxed(val, data->regs + CHANMASK(idx, data->reg_num));
> raw_spin_unlock_irqrestore(&data->lock, flags);
> +
> + pm_runtime_put(dev);
> }
>
> static const struct irq_chip imx_irqsteer_irq_chip = {