linux-kernel - Re: [PATCH 1/2] HID: i2c-hid: The interrupt should be level sensitive

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Message-ID: <20150129200950.GC27265@mail.corp.redhat.com>
Date:	Thu, 29 Jan 2015 15:09:50 -0500
From:	Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	Jiri Kosina <jkosina@...e.cz>, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] HID: i2c-hid: The interrupt should be level sensitive

On Jan 26 2015 or thereabouts, Mika Westerberg wrote:
> The Microsoft HID over I2C specification says two things regarding the
> interrupt:
> 
>  1) The interrupt should be level sensitive
>  2) The device keeps the interrupt asserted as long as it has more reports
>     available.
> 
> We've seen that at least some Atmel and N-Trig panels keep the line low as
> long as they have something to send. The current version of the driver only
> detects the first edge but then fails to read rest of the reports (as the
> line is still asserted).
> 
> Make the driver follow the specification and configure the HID interrupt to
> be level sensitive.
> 
> The Windows HID over I2C driver also seems to do the same.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> ---

FWIW, this one is
Acked-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

looks like we are going to drop 2/2, but this one is still valid.

Cheers,
Benjamin

>  drivers/hid/i2c-hid/i2c-hid.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index d43e967e7533..8f1dfc5c5d9c 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -785,7 +785,7 @@ static int i2c_hid_init_irq(struct i2c_client *client)
>  	dev_dbg(&client->dev, "Requesting IRQ: %d\n", client->irq);
>  
>  	ret = request_threaded_irq(client->irq, NULL, i2c_hid_irq,
> -			IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +			IRQF_TRIGGER_LOW | IRQF_ONESHOT,
>  			client->name, ihid);
>  	if (ret < 0) {
>  		dev_warn(&client->dev,
> -- 
> 2.1.4
> 
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