linux-kernel - Re: [PATCHv2] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

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Date:   Thu, 3 May 2018 11:15:55 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Nick Dyer <nick@...anahar.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Ezequiel Garcia <ezequiel@...labora.com>, kernel@...labora.com
Subject: Re: [PATCHv2] Input: atmel_mxt_ts - fix reset-gpio for level based
 irqs

Hi,

On Mon, Apr 23, 2018 at 01:58:44PM +0200, Sebastian Reichel wrote:
> The current reset-gpio support triggers an interrupt storm on platforms
> using the maxtouch with level based interrupt. The Motorola Droid 4,
> which I used for some of the tests is not affected, since it uses a edge
> based interrupt.
> 
> This change avoids the interrupt storm by enabling the device while its
> interrupt is disabled. Afterwards we wait 100ms. This is important for
> two reasons: The device is unresponsive for some time (~22ms for
> mxt224E) and the CHG (interrupt) line is not working properly for 100ms.
> We don't need to wait for any following interrupts, since the following
> mxt_initialize() checks for bootloader mode anyways.
> 
> This fixes a boot issue on GE PPD (watchdog kills device due to
> interrupt storm) and does not cause regression on Motorola Droid 4.
> 
> Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.co.uk>
> ---
> Changes since PATCHv2:
>  * fix patch description
>  * use same timeout value for soft and gpio-reset
> ---

ping.

-- Sebastian

>  drivers/input/touchscreen/atmel_mxt_ts.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 5d9699fe1b55..f97fbb0af020 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -194,6 +194,8 @@ enum t100_type {
>  
>  /* Delay times */
>  #define MXT_BACKUP_TIME		50	/* msec */
> +#define MXT_RESET_GPIO_TIME	20	/* msec */
> +#define MXT_RESET_INVALID_CHG	100	/* msec */
>  #define MXT_RESET_TIME		200	/* msec */
>  #define MXT_RESET_TIMEOUT	3000	/* msec */
>  #define MXT_CRC_TIMEOUT		1000	/* msec */
> @@ -1206,7 +1208,7 @@ static int mxt_soft_reset(struct mxt_data *data)
>  		return ret;
>  
>  	/* Ignore CHG line for 100ms after reset */
> -	msleep(100);
> +	msleep(MXT_RESET_INVALID_CHG);
>  
>  	mxt_acquire_irq(data);
>  
> @@ -3167,20 +3169,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		return error;
>  	}
>  
> +	disable_irq(client->irq);
> +
>  	if (data->reset_gpio) {
> -		data->in_bootloader = true;
> -		msleep(MXT_RESET_TIME);
> -		reinit_completion(&data->bl_completion);
> +		msleep(MXT_RESET_GPIO_TIME);
>  		gpiod_set_value(data->reset_gpio, 1);
> -		error = mxt_wait_for_completion(data, &data->bl_completion,
> -						MXT_RESET_TIMEOUT);
> -		if (error)
> -			return error;
> -		data->in_bootloader = false;
> +		msleep(MXT_RESET_INVALID_CHG);
>  	}
>  
> -	disable_irq(client->irq);
> -
>  	error = mxt_initialize(data);
>  	if (error)
>  		return error;
> -- 
> 2.17.0
> 

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