Only exit sdw_handle_slave_status() right after calling
sdw_program_device_num() if it actually programmed an ID into at
least one device.
sdw_handle_slave_status() should protect itself against phantom
device #0 ATTACHED indications. In that case there is no actual
device still on #0. The early exit relies on there being a status
change to ATTACHED on the reprogrammed device to trigger another
call to sdw_handle_slave_status() which will then handle the status
of all peripherals. If no device was actually programmed with an
ID there won't be a new ATTACHED indication. This can lead to the
status of other peripherals not being handled.
The status passed to sdw_handle_slave_status() is obviously always
from a point of time in the past, and may indicate accumulated
unhandled events (depending how the bus manager operates). It's
possible that a device ID is reprogrammed but the last PING status
captured state just before that, when it was still reporting on
ID #0. Then sdw_handle_slave_status() is called with this PING info,
just before a new PING status is available showing it now on its new
ID. So sdw_handle_slave_status() will receive a phantom report of a
device on #0, but it will not find one.
Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/soundwire/bus.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 6e569a875a9b..8eded1a55227 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -729,7 +729,7 @@ void sdw_extract_slave_id(struct sdw_bus *bus,
}
EXPORT_SYMBOL(sdw_extract_slave_id);
-static int sdw_program_device_num(struct sdw_bus *bus)
+static int sdw_program_device_num(struct sdw_bus *bus, bool *programmed)
{
u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0};
struct sdw_slave *slave, *_s;
@@ -739,6 +739,8 @@ static int sdw_program_device_num(struct sdw_bus *bus)
int count = 0, ret;
u64 addr;
+ *programmed = false;
+
/* No Slave, so use raw xfer api */
ret = sdw_fill_msg(&msg, NULL, SDW_SCP_DEVID_0,
SDW_NUM_DEV_ID_REGISTERS, 0, SDW_MSG_FLAG_READ, buf);
@@ -797,6 +799,8 @@ static int sdw_program_device_num(struct sdw_bus *bus)
return ret;
}
+ *programmed = true;
+
break;
}
}
@@ -1756,7 +1760,7 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
{
enum sdw_slave_status prev_status;
struct sdw_slave *slave;
- bool attached_initializing;
+ bool attached_initializing, id_programmed;
int i, ret = 0;
/* first check if any Slaves fell off the bus */
@@ -1787,14 +1791,23 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
if (status[0] == SDW_SLAVE_ATTACHED) {
dev_dbg(bus->dev, "Slave attached, programming device number\n");
- ret = sdw_program_device_num(bus);
- if (ret < 0)
- dev_err(bus->dev, "Slave attach failed: %d\n", ret);
+
/*
- * programming a device number will have side effects,
- * so we deal with other devices at a later time
+ * Programming a device number will have side effects,
+ * so we deal with other devices at a later time.
+ * This relies on those devices reporting ATTACHED, which will
+ * trigger another call to this function. This will only
+ * happen if at least one device ID was programmed.
+ * Error returns from sdw_program_device_num() are currently
+ * ignored because there's no useful recovery that can be done.
+ * Returning the error here could result in the current status
+ * of other devices not being handled, because if no device IDs
+ * were programmed there's nothing to guarantee a status change
+ * to trigger another call to this function.
*/
- return ret;
+ sdw_program_device_num(bus, &id_programmed);
+ if (id_programmed)
+ return 0;
}
/* Continue to check other slave statuses */
--
2.30.2
