Re: [PATCH v7 2/2] hwmon: add Altera SoC FPGA hardware monitoring driver

[Guenter Roeck <linux@roeck-us.net>]

On 7/20/26 19:18, tze.yee.ng@altera.com wrote:
> From: Tze Yee Ng <tze.yee.ng@altera.com>
> 
> Add a hardware monitor driver for Altera SoC FPGA devices using the
> Stratix 10 service layer. Sensor channels are selected based on the
> service layer compatible string.
> 
> Signed-off-by: Nazim Amirul <muhammad.nazim.amirul.nazle.asmade@altera.com>
> Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
> ---
...
> +
> +static int socfpga_hwmon_sync_read(struct device *dev,
> +				   enum hwmon_sensor_types type,
> +				   struct stratix10_svc_client_msg *msg)
> +{
> +	struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
> +	int ret;
> +
> +	reinit_completion(&priv->completion);
> +
> +	if (type == hwmon_temp)
> +		priv->client.receive_cb = socfpga_hwmon_readtemp_cb;
> +	else
> +		priv->client.receive_cb = socfpga_hwmon_readvolt_cb;
> +
> +	ret = stratix10_svc_send(priv->chan, msg);
> +	if (ret < 0)
> +		goto status_done;
> +
> +	ret = wait_for_completion_timeout(&priv->completion, HWMON_TIMEOUT);
> +	if (!ret) {
> +		dev_err(priv->client.dev, "timeout waiting for SMC call\n");
> +		/*
> +		 * stratix10_svc_done() stops the worker but does not flush
> +		 * svc_fifo. Wait for the outstanding callback before stopping
> +		 * so a leftover request cannot complete a later sensor read.
> +		 * Discard the late result and still report -ETIMEDOUT.
> +		 */
> +		wait_for_completion(&priv->completion);

Just like Sashiko, I am puzzled and do not understand this code.

Guenter