linux-kernel - Re: [PATCH] usb: typec: tcpci: support edge irq

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Message-ID: <20240828114406.GA27965@francesco-nb>
Date: Wed, 28 Aug 2024 13:44:06 +0200
From: Francesco Dolcini <francesco@...cini.it>
To: Parth Pancholi <parth105105@...il.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Emanuele Ghidoli <emanuele.ghidoli@...adex.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Parth Pancholi <parth.pancholi@...adex.com>
Subject: Re: [PATCH] usb: typec: tcpci: support edge irq

On Wed, Aug 28, 2024 at 01:20:58PM +0200, Parth Pancholi wrote:
> From: Emanuele Ghidoli <emanuele.ghidoli@...adex.com>
> 
> TCPCI USB PHY - PTN5110 could be used with SOCs that only support
> the edge-triggered GPIO interrupts such as TI's K3 device AM69.
> Move the interrupt configuration to the firmware which would
> allow to accommodate edge triggered interrupts for such SOCs.
> In order to support the edge interrupts, register irq line in advance
> and keep track of occurrence during port registering.
> 
> When the edge interrupts are used, it is observed that some of the
> interrupts are missed when tcpci_irq() is serving the current
> interrupt. Therefore, check the status register at the end of
> tcpci_irq() and re-run the function if the status is not clear
> i.e. pending interrupt.
> 
> Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@...adex.com>
> Signed-off-by: Parth Pancholi <parth.pancholi@...adex.com>
> ---
>  drivers/usb/typec/tcpm/tcpci.c | 32 +++++++++++++++++++++++---------
>  1 file changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index a2651a2a7f2e..4537c1d97e8f 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
...

> @@ -915,18 +923,24 @@ static int tcpci_probe(struct i2c_client *client)
>  
>  	chip->data.set_orientation = err;
>  
> -	chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
> -	if (IS_ERR(chip->tcpci))
> -		return PTR_ERR(chip->tcpci);
> -
>  	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
>  					_tcpci_irq,
> -					IRQF_SHARED | IRQF_ONESHOT | IRQF_TRIGGER_LOW,
> +					IRQF_SHARED | IRQF_ONESHOT,
>  					dev_name(&client->dev), chip);
> -	if (err < 0) {
> -		tcpci_unregister_port(chip->tcpci);
> +	if (err < 0)
>  		return err;
> -	}
> +
> +	/*
> +	 * Disable irq while registering port. If irq is configured as an edge
> +	 * irq this allow to keep track and process the irq as soon as it is enabled.
> +	 */
> +	disable_irq(client->irq);
> +
> +	chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
> +	if (IS_ERR(chip->tcpci))
> +		return PTR_ERR(chip->tcpci);
> +
> +	enable_irq(client->irq);

If I undestand this correctly, if tcpci_register_port() fails the irq
stays disabled.

disable_irq(client->irq);
chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
enable_irq(client->irq);

return PTR_ERR_OR_ZERO(chip->tcpci);

maybe?

Francesco