Re: [PATCH] i3c: master: Avoid sending DISEC command with old device address.

From: Frank Li
Date: Tue Aug 20 2024 - 10:49:51 EST


On Tue, Aug 20, 2024 at 10:08:17AM +0530, nxf24178 wrote:

Avoid use nxp nxf24178 as your name, please update it with your real name.

> When a new device hotjoins, a new dynamic address is assigned.
> i3c_master_add_i3c_dev_locked() identifies that the device was previously
> attached to the bus and locates the olddev.
>
> i3c_master_add_i3c_dev_locked()
> {
> ...
> olddev = i3c_master_search_i3c_dev_duplicate(newdev);
> ...
> if (olddev) {
> enable_ibi = true;
> ...
> }
> i3c_dev_free_ibi_locked(olddev);
> ^^^^^^^^
> This function internally calls i3c_dev_disable_ibi_locked(addr)
> function causing to send DISEC command with old Address.
>
> The olddev should not receive any commands on the i3c bus as it
> does not exist and has been assigned a new address. This will
> result in NACK or timeout. So, update the olddev->ibi->enabled
> flag to false to avoid DISEC with OldAddr.
> ...
> }
>
> Signed-off-by: Ravindra Yashvant Shinde <ravindra.yashvant.shinde@xxxxxxx>
> ---
> drivers/i3c/master.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 7028f03c2c42..07ccb2c00074 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -2042,6 +2042,7 @@ int i3c_master_add_i3c_dev_locked(struct i3c_master_controller *master,
> if (olddev->ibi->enabled) {
> enable_ibi = true;
> i3c_dev_disable_ibi_locked(olddev);
> + olddev->ibi->enabled = false;
> }

you can set olddev->ibi->enable = false unconditional. and add comments
about why set it to false here.

Frank

>
> i3c_dev_free_ibi_locked(olddev);
> --
> 2.46.0
>