This is a note to let you know that I've just added the patch titled
ASoC: rockchip: i2s: fix playback after runtime resume
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: asoc-rockchip-i2s-fix-playback-after-runtime-resume.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From c66234cfedfc3e6e3b62563a5f2c1562be09a35d Mon Sep 17 00:00:00 2001
From: John Keeping john@metanate.com Date: Mon, 8 Jan 2018 16:01:04 +0000 Subject: ASoC: rockchip: i2s: fix playback after runtime resume
From: John Keeping john@metanate.com
commit c66234cfedfc3e6e3b62563a5f2c1562be09a35d upstream.
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 Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/soc/rockchip/rockchip_i2s.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/sound/soc/rockchip/rockchip_i2s.c +++ b/sound/soc/rockchip/rockchip_i2s.c @@ -476,6 +476,7 @@ static bool rockchip_i2s_rd_reg(struct d case I2S_INTCR: case I2S_XFER: case I2S_CLR: + case I2S_TXDR: case I2S_RXDR: case I2S_FIFOLR: case I2S_INTSR: @@ -490,6 +491,9 @@ static bool rockchip_i2s_volatile_reg(st switch (reg) { case I2S_INTSR: case I2S_CLR: + case I2S_FIFOLR: + case I2S_TXDR: + case I2S_RXDR: return true; default: return false; @@ -499,6 +503,8 @@ static bool rockchip_i2s_volatile_reg(st static bool rockchip_i2s_precious_reg(struct device *dev, unsigned int reg) { switch (reg) { + case I2S_RXDR: + return true; default: return false; }
Patches currently in stable-queue which might be from john@metanate.com are
queue-4.9/asoc-rockchip-i2s-fix-playback-after-runtime-resume.patch