[alsa-devel] [PATCH v2 01/13] soundwire: Add more documentation

[Vinod Koul]

On Thu, Apr 05, 2018 at 04:37:14PM -0500, Pierre-Louis Bossart wrote:
> On 4/5/18 11:48 AM, Vinod Koul wrote:

> >+SoundWire stream states
> >+-----------------------
> >+
> >+Below shows the SoundWire stream states and state transition diagram. ::
> >+
> >+	+-----------+     +------------+     +----------+     +----------+
> >+	| ALLOCATED +---->| CONFIGURED +---->| PREPARED +---->| ENABLED  |
> >+	|   STATE   |     |    STATE   |     |  STATE   |     |  STATE   |
> >+	+-----------+     +------------+     +----------+     +----+-----+
> >+	                                                           ^
> >+	                                                           |
> >+	                                                           |
> >+	                                                           v
> >+	         +----------+           +------------+        +----+-----+
> >+	         | RELEASED |<----------+ DEPREPARED |<-------+ DISABLED |
> >+	         |  STATE   |           |   STATE    |        |  STATE   |
> >+	         +----------+           +------------+        +----------+
> >+
> 
> Patch 2 describes the states as below:
> 
> +enum sdw_stream_state {
> +	SDW_STREAM_RELEASED = 0,
> +	SDW_STREAM_ALLOCATED = 1,
> +	SDW_STREAM_CONFIGURED = 2,
> +	SDW_STREAM_PREPARED = 3,
> +	SDW_STREAM_ENABLED = 4,
> +	SDW_STREAM_DISABLED = 5,
> +	SDW_STREAM_DEPREPARED = 6,
> 
> which isn't the same picture as the ascii art above. The RELEASED state is
> the starting point, and there's an arrow missing from RELEASED to ALLOCATED.

The enumerator describes the values given for each state. That has no
relation whatsoever to state transitions allowed. I don't recall why people
made SDW_STREAM_RELEASED as Zero, it could very well have been 7 and nothing
changes in diagram.

Now in the last review I did mention to you that there is NO transition
between RELEASED and ALLOCATED, hence no arrow can be made.

Your point on initial state is not right. I can we go ahead and do a
kmalloc() instead of current kzalloc() for the structure which would make
stream state from garbage/uninitialized to ALLOCATED and eventually finally
into RELEASED and it being freed. See no move between ALLOCATED and
RELEASED!

-- 
~Vinod