[PATCH v7 07/15] firmware: arm_scmi: Make polling mode optional

[Cristian Marussi <cristian.marussi@arm.com>]

Add a check for the presence of .poll_done transport operation so that
transports that do not need to support polling mode have no need to provide
a dummy .poll_done callback either and polling mode can be disabled in the
SCMI core for that tranport.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
v6 --> v7
- s/EINVAL/-EINVAL/
- refactored to bail out early when polling mode not supported
---
 drivers/firmware/arm_scmi/driver.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 6c77fcc1bcb7..5ff0bcbb4db4 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -751,6 +751,12 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
 	struct device *dev = info->dev;
 	struct scmi_chan_info *cinfo;
 
+	if (xfer->hdr.poll_completion && !info->desc->ops->poll_done) {
+		dev_warn_once(dev,
+			      "Polling mode is not supported by transport.\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * Initialise protocol id now from protocol handle to avoid it being
 	 * overridden by mistake (or malice) by the protocol code mangling with
@@ -787,7 +793,6 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
 		ktime_t stop = ktime_add_ns(ktime_get(), SCMI_MAX_POLL_TO_NS);
 
 		spin_until_cond(scmi_xfer_done_no_timeout(cinfo, xfer, stop));
-
 		if (ktime_before(ktime_get(), stop)) {
 			unsigned long flags;
 
-- 
2.17.1