linux-kernel - [PATCH 2/3] soundwire: bus: Don't lose unattach notifications

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Date:   Thu, 25 Aug 2022 13:22:40 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <vkoul@...nel.org>, <yung-chuan.liao@...ux.intel.com>,
        <pierre-louis.bossart@...ux.intel.com>, <sanyog.r.kale@...el.com>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH 2/3] soundwire: bus: Don't lose unattach notifications

Ensure that if sdw_handle_slave_status() sees a peripheral
has dropped off the bus it reports it to the client driver.

If there are any devices reporting on address 0 it bails out
after programming the device IDs. So it never reaches the second
loop that calls sdw_update_slave_status().

If the missing device is one that is now showing as unenumerated
it has been given a device ID so will report as attached next
time sdw_handle_slave_status() runs.

With the previous code the client driver would only see another
ATTACHED notification because the UNATTACHED state was lost when
sdw_handle_slave_status() bailed out after programming the
device ID.

This shows up most when the peripheral has to be reset after
downloading updated firmware and there are multiple of these
peripherals on the bus. They will all return to unenumerated state
after the reset, and then there is a mix of unattached, attached
and unenumerated PING states from the peripherals, as each is reset
and they reboot.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
---
 drivers/soundwire/bus.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 704f75c0bae2..bb8ce26c68b3 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -1756,6 +1756,11 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
 			dev_warn(&slave->dev, "Slave %d state check1: UNATTACHED, status was %d\n",
 				 i, slave->status);
 			sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
+
+			/* Ensure driver knows that peripheral unattached */
+			ret = sdw_update_slave_status(slave, status[i]);
+			if (ret < 0)
+				dev_warn(&slave->dev, "Update Slave status failed:%d\n", ret);
 		}
 	}

-- 
2.30.2