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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2020/08/10 18:12:32 UTC

[GitHub] [incubator-nuttx] davids5 opened a new pull request #1553: stm32f7:serial TXDMA ISR was looping on TX Empty

davids5 opened a new pull request #1553:
URL: https://github.com/apache/incubator-nuttx/pull/1553


   ## Summary
   
      Interrupts were blocked 1*n/baud Seconds. The former comment indicates
      there was an assumption that the TXE would be set at DMA completion.
      In reality this is not true. There can be 1 char in the TX Shift
      register and one in the TX holding register, when DMA completes.
      Waiting on TXE is not needed at all. The DMA will resume on the
      DMA req when the TX holding register is written to the TX Shift
      register.
   
   ## Impact
   
   When TX DMA was enabled l loss of data/real time performances. 
   I.E. At 8,1,n,57600 interrupts wee off for 173.61 uS.
   
   ## Testing
   
   Run Linux serial test on PC and NuttX, Scoping the ISR.


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[GitHub] [incubator-nuttx] xiaoxiang781216 merged pull request #1553: stm32f7:serial TXDMA ISR was looping on TX Empty

Posted by GitBox <gi...@apache.org>.

xiaoxiang781216 merged pull request #1553:
URL: https://github.com/apache/incubator-nuttx/pull/1553


   


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