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authorPeter Ujfalusi <peter.ujfalusi@nokia.com>2010-04-23 10:10:01 +0300
committerLiam Girdwood <lrg@slimlogic.co.uk>2010-04-26 15:16:39 +0100
commitf57d2cfaad0d6858d700b5671e01cf3aba6ef779 (patch)
tree592557de5cb0020fc6bc993296c3574a3a3ab233 /kernel/.gitignore
parent76f471274dc9acacd521f151ac9171fd7bbc34c3 (diff)
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ASoC: tlv320dac33: FIFO caused delay reporting
Delay reporting for the three implemented DAC33 FIFO modes. DAC33 has FIFO depth status register(s), but it can not be used, since inside of pcm_pointer we can not send I2C commands. Timestamp based estimation need to be used. The method of calculating the delay depends on the active FIFO mode. Bypass mode: FIFO is bypassed, report 0 as delay Mode1: nSample fill mode. In this mode I need to use two timestamp ts1: taken when the interrupt has been received ts2: taken before writing to nSample register. Interrupts are coming when DAC33 FIFO depth goes under alarm threshold. Phase1: when we received the alarm threshold, but our workqueue has not been executed (safeguard phase). Just count the played out samples since ts1 and subtract it from the alarm threshold value. Phase2: During nSample burst (after writing to nSample register), count the played out samples since ts1, count the samples received since ts2 (in a burst). Estimate the FIFO depth using these and alarm threshold value. Phase3: Draining phase (after the burst read), count the played out samples since ts1. Estimate the FIFO depth using the nSample configuration and the alarm threshold value. Mode7: Threshold based fill mode. In this mode one timestamp is enough. ts1: taken when the interrupt has been received Interrupts are coming when DAC33 FIFO depth reaches upper threshold. Phase1: Draining phase (after the burst), counting the played out samples since ts1, and subtract it from the upper threshold value. Phase2: During burst operation. Using the pre calculated time needed to play out samples from the buffer during the drain period (from upper to lower threshold), move the time window to cover the estimated time from the burst start to the current time. Calculate the samples played out since lower threshold and also the samples received during the same time. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com> Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
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