Re: [alsa-devel] [PATCH 2/3] ALSA SoC: Add mpc5200-psc I2S driver

On Wed, Jul 02, 2008 at 11:19:18AM -0400, Jon Smirl wrote:

On 7/1/08, Grant Likely grant.likely@secretlab.ca wrote:

...

•           /* Due to errata in the i2s mode; need to line up enabling
  

•            * the transmitter with a transition on the frame sync
  

•            * line */
  

•           spin_lock_irqsave(&psc_i2s->lock, flags);
  

•           /* first make sure it is low */
  

•           while ((in_8(&regs->ipcr_acr.ipcr) & 0x80) != 0);
  

Could this be moved to the front of the routine, to increase parallelism?

Once you detect the 0, it will be a fixed interval before the 1 happens. Might as well overlap the computations.

Good point. I'll try this out and see if it remains stable. If this gets done wrong, then left and right channels will often get swapped.

g.