[PATCH] ASoC: fsl_sai: Remove unnecessary FIFO reset in ISR
The FIFO reset drops the words in the FIFO, which may cause channel swap when SAI module is running, especially when the DMA speed is low. So it is not good to do FIFO reset in ISR, then remove the operation.
Fixes: e2681a1bf5ae ("ASoC: fsl_sai: Add isr to deal with error flag") Signed-off-by: Shengjiu Wang shengjiu.wang@nxp.com --- sound/soc/fsl/fsl_sai.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c index d430eece1d6b..a7fa6f0bf83d 100644 --- a/sound/soc/fsl/fsl_sai.c +++ b/sound/soc/fsl/fsl_sai.c @@ -114,11 +114,8 @@ static irqreturn_t fsl_sai_isr(int irq, void *devid) if (flags & FSL_SAI_CSR_SEF) dev_dbg(dev, "isr: Tx Frame sync error detected\n");
- if (flags & FSL_SAI_CSR_FEF) { + if (flags & FSL_SAI_CSR_FEF) dev_dbg(dev, "isr: Transmit underrun detected\n"); - /* FIFO reset for safety */ - xcsr |= FSL_SAI_CSR_FR; - }
if (flags & FSL_SAI_CSR_FWF) dev_dbg(dev, "isr: Enabled transmit FIFO is empty\n"); @@ -148,11 +145,8 @@ static irqreturn_t fsl_sai_isr(int irq, void *devid) if (flags & FSL_SAI_CSR_SEF) dev_dbg(dev, "isr: Rx Frame sync error detected\n");
- if (flags & FSL_SAI_CSR_FEF) { + if (flags & FSL_SAI_CSR_FEF) dev_dbg(dev, "isr: Receive overflow detected\n"); - /* FIFO reset for safety */ - xcsr |= FSL_SAI_CSR_FR; - }
if (flags & FSL_SAI_CSR_FWF) dev_dbg(dev, "isr: Enabled receive FIFO is full\n");
On Tue, Aug 16, 2022 at 10:41 PM Shengjiu Wang shengjiu.wang@nxp.com wrote:
The FIFO reset drops the words in the FIFO, which may cause channel swap when SAI module is running, especially when the DMA speed is low. So it is not good to do FIFO reset in ISR, then remove the operation.
I don't recall the details of adding this many years ago, but leaving underrun/overrun errors unhandled does not sound right to me either. Would it result in a channel swap also? Perhaps there needs to be a reset routine that stops and restarts the DMA as well?
On Wed, Aug 17, 2022 at 2:21 PM Nicolin Chen nicoleotsuka@gmail.com wrote:
On Tue, Aug 16, 2022 at 10:41 PM Shengjiu Wang shengjiu.wang@nxp.com wrote:
The FIFO reset drops the words in the FIFO, which may cause channel swap when SAI module is running, especially when the DMA speed is low. So it is not good to do FIFO reset in ISR, then remove the operation.
I don't recall the details of adding this many years ago, but leaving underrun/overrun errors unhandled does not sound right to me either. Would it result in a channel swap also? Perhaps there needs to be a reset routine that stops and restarts the DMA as well?
Remove the reset, the channel swap is gone.
IMO, no need to handle the underrun/overrun in driver, the SAI hardware can handle the read/write pointer itself when xrun happen, and we don't need reset routine.
For ESAI, because it can't handle read/write pointer correctly when xrun happen, so we need reset routine.
Best regards Wang shengjiu
On Tue, Aug 16, 2022 at 11:29 PM Shengjiu Wang shengjiu.wang@gmail.com wrote:
The FIFO reset drops the words in the FIFO, which may cause channel swap when SAI module is running, especially when the DMA speed is low. So it is not good to do FIFO reset in ISR, then remove the operation.
I don't recall the details of adding this many years ago, but leaving underrun/overrun errors unhandled does not sound right to me either. Would it result in a channel swap also? Perhaps there needs to be a reset routine that stops and restarts the DMA as well?
Remove the reset, the channel swap is gone.
I have no doubt about that :)
IMO, no need to handle the underrun/overrun in driver, the SAI hardware can handle the read/write pointer itself when xrun happen, and we don't need reset routine.
That'd be okay then.
On Wed, 17 Aug 2022 13:24:27 +0800, Shengjiu Wang wrote:
The FIFO reset drops the words in the FIFO, which may cause channel swap when SAI module is running, especially when the DMA speed is low. So it is not good to do FIFO reset in ISR, then remove the operation.
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
Thanks!
[1/1] ASoC: fsl_sai: Remove unnecessary FIFO reset in ISR commit: cb225ac125a9c82889f4796a6092dd0bed39720a
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Thanks, Mark
participants (4)
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Mark Brown -
Nicolin Chen -
Shengjiu Wang -
Shengjiu Wang