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Add a comment about an inherent race with hardware in the Altera JTAG

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UART's low-level console code.
This commit is contained in:
Robert N. M. Watson 2014-08-17 19:43:28 +00:00
parent 70ca316a5d
commit 2ea26cf579
1 changed files with 3 additions and 0 deletions
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3
sys/dev/altera/jtag_uart/altera_jtag_uart_cons.c
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@ -221,6 +221,9 @@ aju_cons_write(char ch)
* disconnection. * disconnection.
* *
* XXXRW: The polling delay may require tuning. * XXXRW: The polling delay may require tuning.
*
* XXXRW: Notice the inherent race with hardware: in clearing the
* bit, we may race with hardware setting the same bit.
*/ */
v = aju_cons_control_read(); v = aju_cons_control_read();
if (v & ALTERA_JTAG_UART_CONTROL_AC) { if (v & ALTERA_JTAG_UART_CONTROL_AC) {