UART driver problem

[Ralf HECKHAUSEN]

I have a strange problem with the uart driver. The 8xx_write in uart.c always fails because copy_from_user returns 0 instead of the requested number of bytes. When I ignore the comparison with the requested number of bytes everything works ok, the correct bytes are transmitted and 8xx_write returns something >0.
The next strange thing: a write to a tty file descriptor sometimes returns a negative number, although the output succeded. perror in this case outputs an unknown error.
Does anyone know this problems?

Ralf


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