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