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

From: Greg KH
Date: Tue May 28 2019 - 19:25:50 EST


On Tue, May 28, 2019 at 03:20:31PM -0500, richard.gong@xxxxxxxxxxxxxxx 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