• Alexander Sverdlin's avatar
    ASoC: cirrus: i2s: IRQ-based stream watchdog · 98e1241c
    Alexander Sverdlin authored
    I2S controller on EP93xx seems to have undocumented HW issue. According to
    "EP93xx User’s Guide", controller can handle underflow and either transmit
    last sample or zeroes in such case until FIFO is filled again. In reality
    undeflow conditions seem to confuse internal state machine from time to
    time and the whole stream gets shifted by one byte (as captured by logic
    analyser on the I2S outputs). One could only hear noise instead of original
    stream and this continues until the FIFO is disabled and enabled again.
    
    Work this around by watching underflow interrupt and resetting I2S TX
    channel + fill FIFO with zero samples until DMA catches up again. This is
    a nasty workaround, but it works. Hence, Kconfig option to disable it in
    case of problems.
    Signed-off-by: default avatarAlexander Sverdlin <alexander.sverdlin@gmail.com>
    Signed-off-by: default avatarMark Brown <broonie@kernel.org>
    98e1241c
Kconfig 2 KB