Serial drivers using DMA (like the atmel_serial driver) tend to get very
confused when the xmit buffer is flushed and nobody told them. They
also tend to spew a lot of garbage since the DMA engine keeps running
after the buffer is flushed and possibly refilled with unrelated data.
This patch adds a new flush_buffer operation to the uart_ops struct,
along with a call to it from uart_flush_buffer() right after the xmit
buffer has been cleared. The driver can implement this in order to
syncronize its internal DMA state with the xmit buffer when the buffer
is flushed.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Update documentation to match reality. INPCK controls whether input
parity checking is enabled.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Improve serial driver documentation:
- Remove CVS id.
- Update pointer to reference driver documentation.
- Add comments about new uart_write_console function.
- Add TIOCM_LOOP modem control bit description.
- Add commentry about enable_ms method being called multiple times.
- Add commentry about startup/shutdown method calling.
- Mention that dereferencing port->info after shutdown is invalid.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The start_tx and stop_tx methods were passed a flag to indicate
whether the start/stop was from the tty start/stop callbacks, and
some drivers used this flag to decide whether to ask the UART to
immediately stop transmission (where the UART supports such a
feature.)
There are other cases when we wish this to occur - when CTS is
lowered, or if we change from soft to hard flow control and CTS
is inactive. In these cases, this flag was false, and we would
allow the transmitter to drain before stopping.
There is really only one case where we want to let the transmitter
drain before disabling, and that's when we run out of characters
to send.
Hence, re-jig the start_tx and stop_tx methods to eliminate this
flag, and introduce new functions for the special "disable and
allow transmitter to drain" case.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch changes the way serial ports are locked when getting modem
status. This change is necessary because we will need to atomically
read the modem status and take action depending on the CTS status.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
