On Fri, Jan 22, 2021 at 10:44 AM mtk15103 [off-list ref] wrote:

On Thu, 2021-01-21 at 20:13 +0800, Nicolas Boichat wrote:

quoted

On Thu, Jan 21, 2021 at 8:09 PM mtk15103 [off-list ref] wrote:

quoted

On Thu, 2021-01-21 at 16:55 +0800, Nicolas Boichat wrote:

quoted

On Thu, Jan 21, 2021 at 3:52 PM Hailong Fan [off-list ref] wrote:

quoted

When flipping the polarity will be generated interrupt under certain
circumstances, but GPIO external signal has not changed.
Then, mask the interrupt before polarity setting, and clear the
unexpected interrupt after trigger type setting completed.

Signed-off-by: Hailong Fan <redacted>
---
Resend since some server reject.
---
 drivers/pinctrl/mediatek/mtk-eint.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/mediatek/mtk-eint.c b/drivers/pinctrl/mediatek/mtk-eint.c
index 22736f60c16c..3acda6bb401e 100644
--- a/drivers/pinctrl/mediatek/mtk-eint.c
+++ b/drivers/pinctrl/mediatek/mtk-eint.c

@@ -157,6 +157,7 @@ static void mtk_eint_ack(struct irq_data *d)
 static int mtk_eint_set_type(struct irq_data *d, unsigned int type)
 {
        struct mtk_eint *eint = irq_data_get_irq_chip_data(d);
+       unsigned int unmask;

bool?

Yes,thanks.

quoted

quoted

        u32 mask = BIT(d->hwirq & 0x1f);
        void __iomem *reg;

@@ -173,6 +174,13 @@ static int mtk_eint_set_type(struct irq_data *d, unsigned int type)
        else
                eint->dual_edge[d->hwirq] = 0;

+       if (!mtk_eint_get_mask(eint, d->hwirq)) {
+               mtk_eint_mask(d);
+               unmask = 1;
+       } else {
+               unmask = 0;
+       }
+
        if (type & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_EDGE_FALLING)) {
                reg = mtk_eint_get_offset(eint, d->hwirq, eint->regs->pol_clr);
                writel(mask, reg);

@@ -189,8 +197,9 @@ static int mtk_eint_set_type(struct irq_data *d, unsigned int type)
                writel(mask, reg);
        }

-       if (eint->dual_edge[d->hwirq])
-               mtk_eint_flip_edge(eint, d->hwirq);

Why are you dropping this? Aren't we at risk to miss the first edge
after mtk_eint_set_type is called?

mtk_eint_unmask() will do it.
If unmask != 1, user need to call mtk_eint_unmask() to enable the
interrupt before use it, thanks.

Makes sense, I just have one more worry:
https://elixir.bootlin.com/linux/latest/source/drivers/pinctrl/mediatek/mtk-eint.c#L122

mtk_eint_unmask unmasks the interrupt _before_ the edge is flipped,
could this cause a spurious interrupt? On any unmask operation -- not
just on mtk_eint_set_type (so this is technically another problem,
that should be fixed as a separate patch)

This situation will not happen.

Spurious interrupt occur condition: edge irq polarity value is same with
input signal.
e.g.
Default value: GPIO input is high, trigger type is falling_edge.
User want modify trigger type is rising_edge under some certain
circumstances, it will generate spurious interrupt but external signal
maintain high.
So we need ack interrupt after trigger_type setting is completed.

mtk_eint_flip_edge is for dual_edge, the polarity setting based on
current gpio input signal:
if (input == high)
        polarity = low; /* falling_edge */
else
        polarity = high; /* rising_edge */
Then it's not cause a spurious interrupt.

Okay let me try to make sure I follow:

- Say interrupt is currently IRQ_TYPE_EDGE_FALLING (and GPIO is high and stable)
- mtk_eint_set_type(d, IRQ_TYPE_EDGE_BOTH)
- mtk_eint_mask(d)
- (no mask changed, just eint->dual_edge)
- mtk_eint_ack(d) (not actually needed in this example)
- mtk_eint_unmask(d)
  - HW reg unmask (can't generate an interrupt as anything that would
have happened is acked already -- even with different previous/new
types than my example)
  - flip_edge (will swap polarity as needed but can't generate
interrupt as it won't set the polarity to be the same as the current
GPIO state)

Okay, I think I'm convinced.

Please fix the nits and then you can add

Reviewed-by: Nicolas Boichat <redacted>

quoted

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+       mtk_eint_ack(d);
+       if (unmask == 1)

Just `if (unmask)`

Yes,thanks.

quoted

quoted

+               mtk_eint_unmask(d);

        return 0;
 }
--
2.18.0

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