linux-kernel - Re: [PATCH] i2c: Allow recovery of the initial IRQ by an I2C client device.

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Date:   Fri, 22 Feb 2019 00:26:10 +0100
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Jim Broadus <jbroadus@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     ckeepax@...nsource.cirrus.com, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: Allow recovery of the initial IRQ by an I2C client
 device.

On Tue, Feb 19, 2019 at 11:30:27AM -0800, Jim Broadus wrote:
> A previous change allowed I2C client devices to discover new IRQs upon
> reprobe by clearing the IRQ in i2c_device_remove. However, if an IRQ was
> assigned in i2c_new_device, that information is lost.
> 
> For example, the touchscreen and trackpad devices on a Dell Inspiron laptop
> are I2C devices whose IRQs are defined by ACPI extended IRQ types. The
> client device structures are initialized during an ACPI walk. After
> removing the i2c_hid device, modprobe fails.
> 
> This change caches the initial IRQ value in i2c_new_device and then resets
> the client device IRQ to the initial value in i2c_device_remove.
> 
> Fixes: 6f108dd70d30 ("i2c: Clear client->irq in i2c_device_remove")
> Signed-off-by: Jim Broadus <jbroadus@...il.com>

Adding Benjamin to CC

> ---
>  drivers/i2c/i2c-core-base.c | 9 +++++----
>  include/linux/i2c.h         | 1 +
>  2 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 28460f6a60cc..af87a16ac3a5 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -430,7 +430,7 @@ static int i2c_device_remove(struct device *dev)
>  	dev_pm_clear_wake_irq(&client->dev);
>  	device_init_wakeup(&client->dev, false);
>  
> -	client->irq = 0;
> +	client->irq = client->init_irq;
>  
>  	return status;
>  }
> @@ -741,10 +741,11 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
>  	client->flags = info->flags;
>  	client->addr = info->addr;
>  
> -	client->irq = info->irq;
> -	if (!client->irq)
> -		client->irq = i2c_dev_irq_from_resources(info->resources,
> +	client->init_irq = info->irq;
> +	if (!client->init_irq)
> +		client->init_irq = i2c_dev_irq_from_resources(info->resources,
>  							 info->num_resources);
> +	client->irq = client->init_irq;
>  
>  	strlcpy(client->name, info->type, sizeof(client->name));
>  
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 65b4eaed1d96..7e748648c7d3 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -333,6 +333,7 @@ struct i2c_client {
>  	char name[I2C_NAME_SIZE];
>  	struct i2c_adapter *adapter;	/* the adapter we sit on	*/
>  	struct device dev;		/* the device structure		*/
> +	int init_irq;			/* irq set at initialization	*/
>  	int irq;			/* irq issued by device		*/
>  	struct list_head detected;
>  #if IS_ENABLED(CONFIG_I2C_SLAVE)
> -- 
> 2.20.1
> 

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