2023-12-14 02:25:01

by Jeff LaBundy

Subject: Re: [PATCH v6] Fix freeze in lm8333 i2c keyboard driver

Hi Tomas,

On Tue, Nov 14, 2023 at 01:30:23PM +0100, Tomas Mudrunka wrote:
> LM8333 uses gpio interrupt line which is active-low.
> When interrupt is set to FALLING edge and button is pressed
> before driver loads, driver will miss the edge and never respond.
> To fix this we should handle ONESHOT LOW interrupt rather than edge.
>
> Rather than hardcoding this, we simply remove the override from
> driver by calling request_threaded_irq() with IRQF_TRIGGER_NONE flag.
> This will keep interrupt trigger configuration as per devicetree. eg.:
>
> lm8333@51 {
> compatible = "ti,lm8333";
> interrupt-parent = <&gpio1>;
> interrupts = <12 IRQ_TYPE_LEVEL_LOW>;
> ...
> }
>
> Signed-off-by: Tomas Mudrunka <[email protected]>
> ---
> drivers/input/keyboard/lm8333.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/input/keyboard/lm8333.c b/drivers/input/keyboard/lm8333.c
> index 7457c3220..c5770ebb2 100644
> --- a/drivers/input/keyboard/lm8333.c
> +++ b/drivers/input/keyboard/lm8333.c
> @@ -179,7 +179,7 @@ static int lm8333_probe(struct i2c_client *client)
> }
>
> err = request_threaded_irq(client->irq, NULL, lm8333_irq_thread,
> - IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> + IRQF_TRIGGER_NONE | IRQF_ONESHOT,

This seems like the best approach; it solves the original problem, and
adopts the correct design pattern of allowing the dts to specify details
about the interrupt polarity and sensitivity.

My only feedback is that I think you can simply drop IRQF_TRIGGER_FALLING
altogether instead of replacing it with IRQF_TRIGGER_NONE; it is pointless
to bitwise OR against zero, and almost no drivers do this. It really should
only be used unless there are quite literally no flags to use. Passing only
IRQF_ONESHOT is sufficient here.

Assuming you agree with this change, please feel free to add the following
for v7:

Reviewed-by: Jeff LaBundy <[email protected]>

> "lm8333", lm8333);
> if (err)
> goto free_mem;
> --
> 2.40.0

Kind regards,
Jeff LaBundy

2023-12-15 16:04:18

by Tomáš Mudruňka

Subject: [PATCH v7] Fix freeze in lm8333 i2c keyboard driver

LM8333 uses gpio interrupt line which is active-low.
When interrupt is set to FALLING edge and button is pressed
before driver loads, driver will miss the edge and never respond.
To fix this we should handle ONESHOT LOW interrupt rather than edge.

Rather than hardcoding this, we simply remove the override from
driver by calling request_threaded_irq() without specifying trigger.
This will keep interrupt trigger configuration as per devicetree. eg.:

lm8333@51 {
compatible = "ti,lm8333";
interrupt-parent = <&gpio1>;
interrupts = <12 IRQ_TYPE_LEVEL_LOW>;
...
}

Signed-off-by: Tomas Mudrunka <[email protected]>
Reviewed-by: Jeff LaBundy <[email protected]>
---
drivers/input/keyboard/lm8333.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/lm8333.c b/drivers/input/keyboard/lm8333.c
index 7457c3220..c5770ebb2 100644
--- a/drivers/input/keyboard/lm8333.c
+++ b/drivers/input/keyboard/lm8333.c
@@ -179,7 +179,7 @@ static int lm8333_probe(struct i2c_client *client)
}

err = request_threaded_irq(client->irq, NULL, lm8333_irq_thread,
- IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+ IRQF_ONESHOT,
"lm8333", lm8333);
if (err)
goto free_mem;
--
2.40.0