Hi,
On Nov 19 2015 19:19, Takashi Iwai wrote:
More specifically, although this patchset can be seen as a "bug fix", the bug you're trying to address isn't clear. And then, what impact this patchset has for users isn't described enough. If there is no usage change, it should be mentioned clearly. If any usage change is expected, it must be written.
I have frequently got private messages from owners of dice-based models since below patchset was merged to mainline, .
[alsa-devel] [PATCH 00/15 v5] ALSA: Enhancement for existed FireWire drivers http://mailman.alsa-project.org/pipermail/alsa-devel/2014-December/085142.ht...
Some of them addressed that ALSA dice driver fails to handle their models. Their experiences are not the same. The summary: * detecting packet discontinuity at starting streaming * ETIMEOUT at starting streaming * ETIMEOUT at probing snd-dice * no sound even if streaming
This patchset is my solution for the issues. In my understanging, the packet discontinuity means that clock generator is not phase-locked, and it costs higher for some models to change the state of clock. The ETIMEOUT means that the driver receive no notification till timeout, and implies the occurence of bus-resets. A part of reasons of no-sound issue is a mismatch of data channel formation in AMDTP packet, and implies failure in probe processing. All of them indicate that it easily occurs to fail to change the state of clock. For the detail, I hope readers to read comments in this patchset.
As a result of applying this patchset, userspace applications cannot start PCM substreams at sampling rates except for current sampling transfer frequency. Instead, they gain stability to start PCM substreams and to probe Dice-based models.
At a glance, it looks the backwards or the regressions. But I believe we should not ignore hardware design, as a device driver developer.
Regards
Takashi Sakamoto