[alsa-devel] Can DMA address, periods, buffer size, etc change after hw_params is called?

Hans-Christian Egtvedt hans-christian.egtvedt at atmel.com
Thu Jan 29 08:18:25 CET 2009


I wonder if I must take care handling changes in DMA address, number of
periods and period size in the prepare callback?

Or are these locked after the first time prepare is called?

The reason I ask is because I'm developing a new ALSA driver and I
prepare a cyclic DMA transfer in the first prepare callback. Additional
calls to prepare will not do anything DMA stuff.

The cyclic DMA transfer is then released in the close callback.

Should I after the open and hw_params calls be ready to handle any
change at all regarding DMA buffer address, periods and/or number of

I hope I made sense in this email (-:

Best regards,
Hans-Christian Egtvedt

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