On Tuesday 27 October 2009 16:00:00 ext Jarkko Nikula wrote:
On Tue, 27 Oct 2009 13:07:23 +0200
Eero Nurkkala ext-eero.nurkkala@nokia.com wrote:
Otherwise, that spinlocking is highly unnecessary and things are far better without than with it. The only case it could be useful is in SMPs, but OMAPs are not such quite yet - and when they are, things will need to be re-though anyway.
Following commit is suggesting that mcbsp code *must* be SMP safe already now:
commit a5b92cc348299c20be215b9f4b50853ecfbf3864 Author: Syed Rafiuddin rafiuddin.syed@ti.com Date: Tue Jul 28 18:57:10 2009 +0530
ARM: OMAP4: Add McBSP support
Yeah, but I think this locking issue has nothing to do with SMP safe or not. On playback start in omap_mcbsp_request the mcbsp->free is cleared. Further modification to the dma_op_mode in dma_op_mode_store is not allowed if the mcbsp port is in use, thus the dma_op_mode is protected against change while the port is in use (ensuring that the mode is same in omap34xx_mcbsp_request and omap_mcbsp_get_dma_op_mode functions). This alone makes the use of spinlock around the dma_op_mode unnecessary.