Re: [PATCHv4 2/4] firmware: add Intel Stratix10 remote system update driver

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, May 28, 2019 at 03:20:31PM -0500, richard.gong@linux.intel.com wrote:
> +/**
> + * rsu_send_msg() - send a message to Intel service layer
> + * @priv: pointer to rsu private data
> + * @command: RSU status or update command
> + * @arg: the request argument, the bitstream address or notify status
> + * @callback: function pointer for the callback (status or update)
> + *
> + * Start an Intel service layer transaction to perform the SMC call that
> + * is necessary to get RSU boot log or set the address of bitstream to
> + * boot after reboot.
> + *
> + * Returns 0 on success or -ETIMEDOUT on error.
> + */
> +static int rsu_send_msg(struct stratix10_rsu_priv *priv,
> +			enum stratix10_svc_command_code command,
> +	unsigned long arg,
> +	void (*callback)(struct stratix10_svc_client *client,
> +			 struct stratix10_svc_cb_data *data))
> +{
> +	struct stratix10_svc_client_msg msg;
> +	int ret;
> +
> +	mutex_lock(&priv->lock);
> +	reinit_completion(&priv->completion);
> +	priv->client.receive_cb = callback;
> +
> +	msg.command = command;
> +	if (arg)
> +		msg.arg[0] = arg;
> +
> +	ret = stratix10_svc_send(priv->chan, &msg);

meta-question, can you send messages that are on the stack and not in
DMA-able memory?  Or should this be a dynamicly created variable so you
know it can work properly with DMA?

And how big is that structure, will it mess with stack sizes?

thanks,

greg k-h