Tom Jewell wrote: > I'm trying to debug some code that implements a feature unit in an > (incoming) USB device, based on an AT32UC3B1256 controller. The feature > unit contains only a volume control, for which the host requests and I > provide values for MAX, MIN, CUR, and RES. The host then tries to set > RES to half the value I've set, even though the host has no business > playing with MAX, MIN, or RES in the device. I don't know what the authors of the USB Audio Class definition were thinking, but they defined the SET_RES request, and so made it the host's business. > So I stall, as the USB audio spec says to do if the device is asked to > modify an unmodifiable quantity. [...] With the stall, the host > repeats the SET_RES request ten times at the same value, half of what > I've defined RES to be. Those repeats are a workaround for devices that timeout on some control requests, but they should not be done for stalls. > The upshot is that when the feature unit shows up (e.g. in xfce4 mixer) > it's missing the slider; it just shows a mute button. This has probably nothing to do with the SET_RES requests. What are the outputs of "lsusb -v" and "amixer contents" for this control? Are there any error messages in the system log? Regards, Clemens ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
