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SubjectRe: [PATCH] i2c: Allow recovery of the initial IRQ by an I2C client device.
Apologies.. This should have been marked v2.

On Tue, Feb 19, 2019 at 11:30 AM Jim Broadus <jbroadus@gmail.com> 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@gmail.com>
> ---
> 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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