[1/2] pinctrl: mediatek: Ignore interrupts that are wake only during resume

Before suspending, mtk-eint would set the interrupt mask to the
one in wake_mask. However, some of these interrupts may not have a
corresponding interrupt handler, or the interrupt may be disabled.

On resume, the eint irq handler would trigger nevertheless,
and irq/pm.c:irq_pm_check_wakeup would be called, which would
try to call irq_disable. However, if the interrupt is not enabled
(irqd_irq_disabled(&desc->irq_data) is true), the call does nothing,
and the interrupt is left enabled in the eint driver.

Especially for level-sensitive interrupts, this will lead to an
interrupt storm on resume.

If we detect that an interrupt is only in wake_mask, but not in
cur_mask, we can just mask it out immediately (as mtk_eint_resume
would do anyway at a later stage in the resume sequence, when
restoring cur_mask).

Fixes: bf22ff45bed ("genirq: Avoid unnecessary low level irq function calls")
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
---
 drivers/pinctrl/mediatek/mtk-eint.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

Hi Nicolas,

On Sun, Apr 28, 2019 at 8:55 PM Nicolas Boichat <drinkcat@chromium.org> wrote:
>
> Before suspending, mtk-eint would set the interrupt mask to the
> one in wake_mask. However, some of these interrupts may not have a
> corresponding interrupt handler, or the interrupt may be disabled.
>
> On resume, the eint irq handler would trigger nevertheless,
> and irq/pm.c:irq_pm_check_wakeup would be called, which would
> try to call irq_disable. However, if the interrupt is not enabled
> (irqd_irq_disabled(&desc->irq_data) is true), the call does nothing,
> and the interrupt is left enabled in the eint driver.
>
> Especially for level-sensitive interrupts, this will lead to an
> interrupt storm on resume.
>
> If we detect that an interrupt is only in wake_mask, but not in
> cur_mask, we can just mask it out immediately (as mtk_eint_resume
> would do anyway at a later stage in the resume sequence, when
> restoring cur_mask).
>
> Fixes: bf22ff45bed ("genirq: Avoid unnecessary low level irq function calls")
> Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>

Acked-by: Sean Wang <sean.wang@kernel.org>

> ---
>  drivers/pinctrl/mediatek/mtk-eint.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pinctrl/mediatek/mtk-eint.c b/drivers/pinctrl/mediatek/mtk-eint.c
> index f464f8cd274b75c..737385e86beb807 100644
> --- a/drivers/pinctrl/mediatek/mtk-eint.c
> +++ b/drivers/pinctrl/mediatek/mtk-eint.c
> @@ -318,7 +318,7 @@ static void mtk_eint_irq_handler(struct irq_desc *desc)
>         struct irq_chip *chip = irq_desc_get_chip(desc);
>         struct mtk_eint *eint = irq_desc_get_handler_data(desc);
>         unsigned int status, eint_num;
> -       int offset, index, virq;
> +       int offset, mask_offset, index, virq;
>         void __iomem *reg =  mtk_eint_get_offset(eint, 0, eint->regs->stat);
>         int dual_edge, start_level, curr_level;
>
> @@ -328,10 +328,24 @@ static void mtk_eint_irq_handler(struct irq_desc *desc)
>                 status = readl(reg);
>                 while (status) {
>                         offset = __ffs(status);
> +                       mask_offset = eint_num >> 5;
>                         index = eint_num + offset;
>                         virq = irq_find_mapping(eint->domain, index);
>                         status &= ~BIT(offset);
>
> +                       /*
> +                        * If we get an interrupt on pin that was only required
> +                        * for wake (but no real interrupt requested), mask the
> +                        * interrupt (as would mtk_eint_resume do anyway later
> +                        * in the resume sequence).
> +                        */
> +                       if (eint->wake_mask[mask_offset] & BIT(offset) &&
> +                           !(eint->cur_mask[mask_offset] & BIT(offset))) {
> +                               writel_relaxed(BIT(offset), reg -
> +                                       eint->regs->stat +
> +                                       eint->regs->mask_set);
> +                       }
> +
>                         dual_edge = eint->dual_edge[index];
>                         if (dual_edge) {
>                                 /*
> --
> 2.21.0.593.g511ec345e18-goog
>

On Mon, Apr 29, 2019 at 5:55 AM Nicolas Boichat <drinkcat@chromium.org> wrote:

> Before suspending, mtk-eint would set the interrupt mask to the
> one in wake_mask. However, some of these interrupts may not have a
> corresponding interrupt handler, or the interrupt may be disabled.
>
> On resume, the eint irq handler would trigger nevertheless,
> and irq/pm.c:irq_pm_check_wakeup would be called, which would
> try to call irq_disable. However, if the interrupt is not enabled
> (irqd_irq_disabled(&desc->irq_data) is true), the call does nothing,
> and the interrupt is left enabled in the eint driver.
>
> Especially for level-sensitive interrupts, this will lead to an
> interrupt storm on resume.
>
> If we detect that an interrupt is only in wake_mask, but not in
> cur_mask, we can just mask it out immediately (as mtk_eint_resume
> would do anyway at a later stage in the resume sequence, when
> restoring cur_mask).
>
> Fixes: bf22ff45bed ("genirq: Avoid unnecessary low level irq function calls")
> Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>

Patch applied for fixes.
Hm a late ACK made me miss this, sorry.

Yours,
Linus Walleij