linux-kernel - [PATCH v2 2/5] soundwire: add enumeration

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Message-Id: <20191106190034.4619-3-pierre-louis.bossart@linux.intel.com>
Date:   Wed,  6 Nov 2019 13:00:31 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     alsa-devel@...a-project.org
Cc:     linux-kernel@...r.kernel.org, tiwai@...e.de, broonie@...nel.org,
        vkoul@...nel.org, gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: [PATCH v2 2/5] soundwire: add enumeration_complete structure

We need an async mechanism to prevent access to Slaves that are not
fully-enumerated.

init_completion() will be invoked when the Slave becomes UNATTACHED,
and complete() will be invoked when the state become ATTACHED. Any
read/write before this status change will be delayed with a
wait_for_completion().

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
 include/linux/soundwire/sdw.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index a381a596212b..2c6688eb4c09 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -549,6 +549,9 @@ struct sdw_slave_ops {
  * @probe_complete: completion utility to control potential races
  * on startup between driver probe/initialization and SoundWire
  * Slave state changes/imp-def interrupts
+ * @enumeration_complete: completion utility to control potential races
+ * on startup between device enumeration and read/write access to the
+ * Slave device
  */
 struct sdw_slave {
 	struct sdw_slave_id id;
@@ -565,6 +568,7 @@ struct sdw_slave {
 	u16 dev_num;
 	bool probed;
 	struct completion probe_complete;
+	struct completion enumeration_complete;
 };
 
 #define dev_to_sdw_dev(_dev) container_of(_dev, struct sdw_slave, dev)
-- 
2.20.1