Re: [PATCH] accel/ivpu: Document why full JSM message size is always used

[Dawid Osuchowski <dawid.osuchowski@linux.intel.com>]

On 2026-05-22 11:32 AM, Karol Wachowski wrote:
> Firmware expects IPC messages to always carry the full fixed
> sizeof(struct vpu_jsm_msg) size. Sending the full struct also
> ensures unused fields are zeroed, which maintains compatibility
> when existing commands are extended with new fields in the future.
> 
> Replace the misleading TODO comment with an explanation of the
> actual intent.
> 
> Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>

Reviewed-by: Dawid Osuchowski <dawid.osuchowski@linux.intel.com>

> ---
>   drivers/accel/ivpu/ivpu_ipc.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/accel/ivpu/ivpu_ipc.c b/drivers/accel/ivpu/ivpu_ipc.c
> index f47df092bb0d..9f1ba0c57442 100644
> --- a/drivers/accel/ivpu/ivpu_ipc.c
> +++ b/drivers/accel/ivpu/ivpu_ipc.c
> @@ -97,7 +97,11 @@ ivpu_ipc_tx_prepare(struct ivpu_device *vdev, struct ivpu_ipc_consumer *cons,
>   
>   	memset(tx_buf, 0, sizeof(*tx_buf));
>   	tx_buf->ipc.data_addr = jsm_vpu_addr;
> -	/* TODO: Set data_size to actual JSM message size, not union of all messages */
> +	/*
> +	 * Firmware expects full JSM message size regardless of the payload size.
> +	 * Unused fields must be zeroed to allow future extensions of existing
> +	 * commands without breaking compatibility.
> +	 */
>   	tx_buf->ipc.data_size = sizeof(*req);
>   	tx_buf->ipc.channel = cons->channel;
>   	tx_buf->ipc.src_node = 0;