lkml.org 
[lkml]   [2017]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 04/14] soundwire: Add MIPI DisCo property helpers
On Fri, Nov 24, 2017 at 09:34:49PM +0530, Sanyog Kale wrote:
> On Thu, Nov 23, 2017 at 02:38:12PM +0000, Charles Keepax wrote:
> > On Fri, Nov 10, 2017 at 05:19:06PM +0530, Vinod Koul wrote:
>
> > > MIPI Discovery And Configuration (DisCo) Specification for SoundWire
> > > specifies properties to be implemented for SoundWire Masters and
> > > Slaves. The DisCo spec doesn't mandate these properties. However,
> > > SDW bus cannot work without knowing these values.
> > >
> > > The helper functions read the Master and Slave properties.
> > > Implementers of Master or Slave drivers can use any of the below
> > > three mechanisms:
> > > a) Use these APIs here as .read_prop() callback for Master
> > > and Slave
> > > b) Implement own methods and set those as .read_prop(), but invoke
> > > APIs in this file for generic read and override the values with
> > > platform specific data
> > > c) Implement ones own methods which do not use anything provided
> > > here
> > >
> > > Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
> > > Signed-off-by: Vinod Koul <vinod.koul@intel.com>
> > > ---
> > Apologies for the long and slightly vague comment, but I guess my
> > question is do you have a thought on how drivers should know when
> > it is safe to communicate with a SoundWire device?
>
> IMO it is safe to communicate with SoundWire device when the Slave
> status is ATTACHED. In any case bus will report error if it is not able
> to communicate with SoundWire device.
>

Yeah I guess my point here is that there is currently no way in
this SoundWire framework for the slave driver to know if the
device is attached or not, unless I am missing something? There
are calls by which the master can inform the framework, but
nothing to pass that on to the slave driver.

I would indeed imagine the comms would fail if the slave isn't
attached but that doesn't seem like a particularly robust way of
determining that.

Thanks,
Charles

\
 
 \ /
  Last update: 2017-11-27 09:02    [W:0.074 / U:1.220 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site