[PATCH] soundwire: stream: validate slave port against DisCo port bitmap

[Eric Wu <kunjinkao.jp@gmail.com>]

sdw_slave_port_config() checks that the port number falls in the
generic valid range, but never checks whether the Slave actually
exposes that port for the requested direction. An in-range but
unsupported port number (or the right port with the wrong direction)
gets accepted without complaint.

sdw_get_slave_dpn_prop() already does this lookup against the
source_ports/sink_ports bitmaps for other purposes, so reuse it here
instead of open-coding a new check.

Slaves that don't report source_ports/sink_ports at all (both zero)
are left unchecked, since that's treated elsewhere in the driver as
"property not provided" rather than "no ports supported".

Signed-off-by: Eric Wu <kunjinkao.jp@gmail.com>
---
Only compile-tested: x86_64 gcc, arm64 and arm32 clang (LLVM=1),
all clean with W=1. I do not have SoundWire hardware to test with.

 drivers/soundwire/stream.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 4ed8fb7663ad..30cb8a8552d8 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -1054,14 +1054,23 @@ static int sdw_slave_port_config(struct sdw_slave *slave,
 
 	i = 0;
 	list_for_each_entry(p_rt, &s_rt->port_list, port_node) {
-		/*
-		 * TODO: Check valid port range as defined by DisCo/
-		 * slave
-		 */
 		if (!is_bpt_stream) {
 			ret = sdw_slave_port_is_valid_range(&slave->dev, port_config[i].num);
 			if (ret < 0)
 				return ret;
+
+			/*
+			 * source_ports/sink_ports are optional DisCo properties:
+			 * both zero means "not provided" rather than "no ports",
+			 * so only enforce the check when the Slave reports them.
+			 */
+			if ((slave->prop.source_ports || slave->prop.sink_ports) &&
+			    !sdw_get_slave_dpn_prop(slave, s_rt->direction, port_config[i].num)) {
+				dev_err(&slave->dev, "port %d not supported for %s\n",
+					port_config[i].num,
+					s_rt->direction == SDW_DATA_DIR_TX ? "TX" : "RX");
+				return -EINVAL;
+			}
 		} else if (port_config[i].num) {
 			return -EINVAL;
 		}
-- 
2.25.1