Re: [PATCH] extcon: usbc-tusb320: make sure the state is initialized on probe

From: Peter Rosin
Date: Tue Aug 23 2022 - 08:42:33 EST


Hi!

2022-06-30 at 08:03, Peter Rosin wrote:
> Hi!
>
> 2022-06-29 at 21:54, Chanwoo Choi wrote:
>> On 22. 6. 23. 20:21, Peter Rosin wrote:
>>> When the port is connected at boot, there is not necessarily
>>> an interrupt flagged in the interrupt status register, causing
>>> the IRQ handler to bail out early without reading the state when
>>> it is invoked directly from probe.
>>>
>>> Add a flag that overrides the interrupt status register and reads
>>> the state regardless during probe.
>>>
>>> Fixes: 06bc4ca115cd ("extcon: Add driver for TI TUSB320")
>>> Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>
>>> ---
>>> drivers/extcon/extcon-usbc-tusb320.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/extcon/extcon-usbc-tusb320.c b/drivers/extcon/extcon-usbc-tusb320.c
>>> index 6ba3d89b106d..bd3645ae0d52 100644
>>> --- a/drivers/extcon/extcon-usbc-tusb320.c
>>> +++ b/drivers/extcon/extcon-usbc-tusb320.c
>>> @@ -55,6 +55,7 @@ struct tusb320_priv {
>>> struct extcon_dev *edev;
>>> struct tusb320_ops *ops;
>>> enum tusb320_attached_state state;
>>> + bool initialized;
>>> };
>>>
>>> static const char * const tusb_attached_states[] = {
>>> @@ -195,7 +196,7 @@ static irqreturn_t tusb320_irq_handler(int irq, void *dev_id)
>>> return IRQ_NONE;
>>> }
>>>
>>> - if (!(reg & TUSB320_REG9_INTERRUPT_STATUS))
>>> + if (priv->initialized && !(reg & TUSB320_REG9_INTERRUPT_STATUS))
>>> return IRQ_NONE;
>
> Do not return early if priv->initialized is false. Behave as before if
> priv->initialized is true.
>
>>>
>>> state = (reg >> TUSB320_REG9_ATTACHED_STATE_SHIFT) &
>>> @@ -297,6 +298,8 @@ static int tusb320_extcon_probe(struct i2c_client *client,
>>> */
>>> tusb320_irq_handler(client->irq, priv);
>>>
>>> + priv->initialized = true;
>>> +
>>
>> After initializing as 'priv->initialized = true',
>> tusb320_irq_handler() is not anymore detecting the external connector changes.
>
> Have you tested the patch and observed the trouble you are reporting, or
> have you simply misread the patch?
>
>>
>> If external connector is detached after finished kernel boot,
>> how to change the state of external connector by using extcon_set_state()?
>>
>
> If you did test this and there actually is a problem, maybe there should be
> READ_ONCE in the irq handler when checking and WRITE_ONCE when assigning
> priv->initialized. But if that's really what's going on I'd be surprised
> when it's a variable that changes *once* before the interrupt has even
> been requested.
>
> Cheers,
> Peter

Ping?

Cheers,
Peter