On Sun, Jul 20, 2008 at 03:51:20PM -0400, Jon Smirl wrote: > > The issue is the time taken to do the I/O via the I2C bus, not the > > implementation in the chip - if anything I'd expect this to be slower > > than a direct hardware implementation but not perceptibly. If > > applications try to step through all the values for a control with > > anything approaching the available resolution then that'd be a lot of > > data being written. Like I say, it may not be a practical issue (I'd > > expect applications to be smarter) but it raised my eyebrows. > Yes, stepping through 4096 volume levels individually would be a pain. > A UI would need to initially move in larger increments. > I have thought about building a pseudo interface for the chip that > would be compatible with the existing ASLA controls, and then using an I'd just ignore it initially and if it's a problem look at doing things like deferring the register writes by a short amount. Most UIs won't be able to display anything like the resolution required to cause trouble in the first place - they are scaling the resolution of the control into the resolution of the UI anyway. > IOCTL to bypass for finer control. But isn't this problem going to > reoccur as we encounter more HD audio level hardware? My own expectation would be that if it is a serious issue it'll be dealt with in user space - my concern here was that the effects are being magnified by the combination of the slow control bus and the large registers that contain the controls. As I say, it may not be a real issue. > > > 0x49-0x50, bass management > > > 4 bytes, contain 5.23 coefficients ... > > OK, so the bass management looks like it should be able to fit in a > > processor word? > If the word is 64 bits. Err... you said it's 4 bytes? > To support this chip you could add the concept of fields to ALSA ASoC? > registers. Fields would be 32 bit. For backward compatibility the > existing chips would just set field to 0. The use of a shift plus mask is largely a function of the fact that that maps well onto how datasheets are usually written - I'm not sure that using numbered fields would help there. I'm also not sure that it's a good idea to build the 32 bit assumption in - someone is bound to come up with controls that are either larger that or cross a 32 bit boundary within a register. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
