@@ -504,6 +504,7 @@ static bool rockchip_i2s_rd_reg(struct device *dev, unsigned int reg)
case I2S_INTCR:
case I2S_XFER:
case I2S_CLR:
+ case I2S_TXDR:
case I2S_RXDR:
case I2S_FIFOLR:
case I2S_INTSR:
@@ -518,6 +519,9 @@ static bool rockchip_i2s_volatile_reg(struct device *dev, unsigned int reg)
switch (reg) {
case I2S_INTSR:
case I2S_CLR:
+ case I2S_FIFOLR:
+ case I2S_TXDR:
+ case I2S_RXDR:
return true;
default:
return false;
@@ -527,6 +531,8 @@ static bool rockchip_i2s_volatile_reg(struct device *dev, unsigned int reg)
static bool rockchip_i2s_precious_reg(struct device *dev, unsigned int reg)
{
switch (reg) {
+ case I2S_RXDR:
+ return true;
default:
return false;
}
When restoring registers during runtime resume, we must not write to I2S_TXDR which is the transmit FIFO as this queues up a sample to be output and pushes all of the output channels down by one. This can be demonstrated with the speaker-test utility: for i in a b c; do speaker-test -c 2 -s 1; done which should play a test through the left speaker three times but if the I2S hardware starts runtime suspended the first sample will be played through the right speaker. Fix this by marking I2S_TXDR as volatile (which also requires marking it as readble, even though it technically isn't). This seems to be the most robust fix, the alternative of giving I2S_TXDR a default value is more fragile since it does not prevent regcache writing to the register in all circumstances. While here, also fix the configuration of I2S_RXDR and I2S_FIFOLR; these are not writable so they do not suffer from the same problem as I2S_TXDR but reading from I2S_RXDR does suffer from a similar problem. Fixes: f0447f6cbb20 ("ASoC: rockchip: i2s: restore register during runtime_suspend/resume cycle", 2016-09-07) Signed-off-by: John Keeping <john@metanate.com> --- v2 changes: - Fix rockchip_i2s_precious_reg to return true for I2S_RXDR sound/soc/rockchip/rockchip_i2s.c | 6 ++++++ 1 file changed, 6 insertions(+)