serial: msm_serial: Fix kgdb continue
Frank reports that after continuing in kgdb the RX stale event doesn't occur until after the RX fifo is filled up with exactly the amount of characters programmed for the RX watermark (in this case it's 48). To read a single character from the uartdm hardware we force a stale event so that any characters in the RX packing buffer are flushed into the RX fifo immediately instead of waiting for a stale timeout or for the fifo to fill. Forcing that stale event asserts the stale interrupt but we never clear that interrupt via UART_CR_CMD_RESET_STALE_INT in the polling functions. So when kgdb continues the stale interrupt is left pending in the hardware and we don't timeout with a stale event, like we usually would if a user typed one character on the console, until the reset stale interrupt and stale event commands are sent. Frank could get things working again by running handle_rx_dm(). By putting enough characters into the fifo he could trigger a watermark interrupt, and thus cause handle_rx_dm() to run finally resetting the stale interrupt and enabling the stale event so that single characters would cause timeouts again. The fix is to just do what the interrupt routine was doing all along and clear the stale interrupt and enable the event again. Doing this also smooths over any differences in the fifo behavior between v1.3 and v1.4 hardware allowing us to skip forcing the uart into single character mode. Reviewed-by:Frank Rowand <frank.rowand@sonymobile.com> Tested-by:
Stephen Boyd <sboyd@codeaurora.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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