Commands sent to device occasionaly fail

[bmegli]

Commands like vmu_stream may occasionally fail returing VMU_ERROR (correctly) but not setting errno (incorrectly)

[bmegli]

This seems to happen when:

• command is sent to device but ignored
• library checks if the command was applied and notices that it had no effect

This means that there was no IO error noticeable from host side but the command didn't have expected effect

[bmegli]

The way to fix it would be (on vmu_stream example)

• just store the settings requested by user
• while reading from the device if settings requested by user are different from those on device send commands to make them equal

So vmu_stream would return immediately and the library would handle internally all the communication with the device while reading data.

This approach is ok for vmu_stream but for vmu_resolution there would be time when device would stream data with different resolution then user expects (between setting requested resolution and commanding it to device)