On Wed, 19 May 2010 15:27:35 +0300 Peter Ujfalusi peter.ujfalusi@nokia.com wrote:
The sysfs set interface implies userspace having knowledge of driver capabilities and configuration in order to safely toggle between the two DMA modes. Imo, the mcbsp client driver should be the only entity configuring it's DMA modes (in a safe manner) depending on the use case.
Furthermore, if there is a need for 'Use Cases', than the machine driver can provide user control to switch between them. The thing is that in most cases these are trivial, and mostly the same settings, but if you throw a codec like the tlv320dac33 into the mix, which has it's own FIFO, than things gets complicated. The user (the real one, not the developer) has several settings scattered all around the place, and those has to be configured in harmony. The only place is to do this, is in the machine driver, whihc than can build up 'scenarios', and configure the things in synchronized manner.
Yes and I think only very few developers know what to do with those op mode and threshold sysfs controls so most probably they are unused. Then machine drivers setting them automatically/with some control could give us more testing base.
But as those sysfs controls are there we must preserve them for a release cycle or two in case if someone is using them. At least Linus or Andrew may complain about removal of them.