[RTEMS Project] #2733: raspberrypi: SPI driver has several flaws

[RTEMS trac]

#2733: raspberrypi: SPI driver has several flaws
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 Reporter:  soja     |      Owner:
     Type:  defect   |     Status:  new
 Priority:  normal   |  Milestone:  4.12
Component:  General  |    Version:  4.12
 Severity:  normal   |   Keywords:  spi raspberrypi driver
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 I started to work with the SPI of the raspberry pi and noticed several
 problems with the current driver after recording the frames with a logic
 analyzer:

 - Setting the chip select signal using the CSPOL-bits of the control
 register creates incorrect chip select signals
 - After every byte written to the TX FIFO buffer the driver waits for a
 signal from an interrupt. This creates very long pauses between
 consecutive bytes.
 - The lsb-first mode does not look as if it would work
 - 3-wire/bidirectional mode might not work
 - Accessing the driver from a different thread than the one which called
 spi_init will cause a deadlock
 - Simultaneous read-write-operation is not supported

 I will submit a patchset for this after some testing.

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Ticket URL: <http://devel.rtems.org/ticket/2733>
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