linux-kernel - Re: [PATCH] Input: elants_i2c - do not clobber interrupt trigger on x86

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Date:   Tue, 28 Nov 2017 17:27:03 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org
Cc:     Johnny Chuang <johnny.chuang@....com.tw>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: elants_i2c - do not clobber interrupt trigger on
 x86

On 11/16/2017 05:24 PM, Dmitry Torokhov wrote:
> This is similar to commit a4b0a58bb142 ("Input: elan_i2c - do not
> clobber interrupt trigger on x86")
> 
> On x86 we historically used falling edge interrupts in the driver
> because that's how first Chrome devices were configured. They also
> did not use ACPI to enumerate I2C devices (because back then there
> was no kernel support for that), so trigger was hard-coded in the
> driver. However the controller behavior is much more reliable if
> we use level triggers, and that is how we configured ARM devices,
> and how want to configure newer x86 devices as well. All newer
> x86 boxes have their I2C devices enumerated in ACPI.
> 
> Let's see if platform code (ACPI, DT) described interrupt and
> specified particular trigger type, and if so, let's use it instead
> of always clobbering trigger with IRQF_TRIGGER_FALLING. We will
> still use this trigger type as a fallback if platform code left
> interrupt trigger unconfigured.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>'

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>   drivers/input/touchscreen/elants_i2c.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
> index e102d7764bc2..1cc3e6b135e7 100644
> --- a/drivers/input/touchscreen/elants_i2c.c
> +++ b/drivers/input/touchscreen/elants_i2c.c
> @@ -1261,10 +1261,13 @@ static int elants_i2c_probe(struct i2c_client *client,
>   	}
>   
>   	/*
> -	 * Systems using device tree should set up interrupt via DTS,
> -	 * the rest will use the default falling edge interrupts.
> +	 * Platform code (ACPI, DTS) should normally set up interrupt
> +	 * for us, but in case it did not let's fall back to using falling
> +	 * edge to be compatible with older Chromebooks.
>   	 */
> -	irqflags = client->dev.of_node ? 0 : IRQF_TRIGGER_FALLING;
> +	irqflags = irq_get_trigger_type(client->irq);
> +	if (!irqflags)
> +		irqflags = IRQF_TRIGGER_FALLING;
> `
>   	error = devm_request_threaded_irq(&client->dev, client->irq,
>   					  NULL, elants_i2c_irq,
>