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cbfea84f82
Clear the CDNS_MCP_INT_RX_WL interrupt before signaling completion.
This is to prevent the potential race where:
- The main thread is scheduled immediately the completion is signaled,
and starts a new message
- The RX_WL IRQ for this new message happens before sdw_cdns_irq() has
been re-scheduled.
- When sdw_cdns_irq() is re-scheduled it clears the new RX_WL interrupt.
MAIN THREAD | IRQ THREAD
|
_cdns_xfer_msg() |
{ |
write data to FIFO |
wait_for_completion_timeout() |
<BLOCKED> | <---- RX_WL IRQ
| sdw_cdns_irq()
| {
| signal completion
<== RESCHEDULE <==
Handle message completion |
} |
|
Start new message |
_cdns_xfer_msg() |
{ |
write data to FIFO |
wait_for_completion_timeout() |
<BLOCKED> | <---- RX_WL IRQ
==> RESCHEDULE ==>
| // New RX_WL IRQ is cleared before
| // it has been handled.
| clear CDNS_MCP_INTSTAT
| return IRQ_HANDLED;
| }
Before this change, this error message was sometimes seen on kernels
that have large amounts of debugging enabled:
SCP Msg trf timed out
This error indicates that the completion has not been signalled after
500ms.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 956baa1992 ("soundwire: cdns: Add sdw_master_ops and IO transfer support")
Reported-by: Norman Bintang <normanbt@google.com>
Closes: https://issuetracker.google.com/issues/477099834
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Link: https://patch.msgid.link/20260310113133.1707288-1-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
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