serial: sh-sci: Fix race condition causing garbage during shutdown

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If DMA is enabled and used, a burst of old data may be seen on the
serial console during "poweroff" or "reboot".  uart_flush_buffer()
clears the circular buffer, but sci_port.tx_dma_len is not reset.
This leads to a circular buffer overflow, dumping (UART_XMIT_SIZE -
sci_port.tx_dma_len) bytes.

To fix this, add a .flush_buffer() callback that resets
sci_port.tx_dma_len.

Inspired by commit 31ca2c63fd ("tty/serial: atmel: fix race
condition (TX+DMA)").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Geert Uytterhoeven 2017-04-25 20:15:35 +02:00 • committed by Greg Kroah-Hartman

parent 7fbcf3afe6

commit 1cf4a7efdc

1 changed files with 14 additions and 2 deletions

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drivers/tty/serial/sh-sci.c

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