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Subject[PATCH 0/6] parport_pc: Fixes for Oxford Semiconductor PCI/e parallel ports
Hi,

After several iterations I have now finally made my PCIe parallel port
option card based on the Oxford Semiconductor OXPCIe952 ASIC work with my
RISC-V system.

This has turned out a generic incompatibility issue between our driver
and somewhat quirky OxSemi hardware giving the same symptoms with an x86
system as well, where the driver tries to use the Parallel Port FIFO mode,
which is indeed documented by the relevant datasheets as not supported by
OxSemi hardware.

Additionally the hardware requires a specific bit pattern to be written
into low 5 bits of ECR while poking at the mode in the high 3 bits, and
while the OXPCIe952 implementation does not appear sensitive to it older
ones seem to and may lock up according to our own history.

This small patch series addresses these problems in 6 incremental steps.
See individual change descriptions for further details. I have verified
these changes with and w/o PARPORT_PC_FIFO and PARPORT_1284 options set.
Please apply.

Maciej

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