Hi Laurent, Matsuoka-san,
On Sat, Aug 22, 2015 at 1:17 AM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> On Friday 21 August 2015 20:25:43 Geert Uytterhoeven wrote:
>> Make sure the transmitter and receiver are stopped when shutting down
>> the port, to avoid new RX DMA requests to arrive.
>>
>> Inspired by a patch in the BSP by Koji Matsuoka
>> <koji.matsuoka.xm@xxxxxxxxxxx>.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
>> index d8b73e791a554823..0622cafaf1c71cab 100644
>> --- a/drivers/tty/serial/sh-sci.c
>> +++ b/drivers/tty/serial/sh-sci.c
>> @@ -1820,12 +1820,16 @@ static void sci_shutdown(struct uart_port *port)
>> {
>> struct sci_port *s = to_sci_port(port);
>> unsigned long flags;
>> + u16 scscr;
>>
>> dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
>>
>> spin_lock_irqsave(&port->lock, flags);
>> sci_stop_rx(port);
>> sci_stop_tx(port);
>> + scscr = serial_port_in(port, SCSCR);
>> + scscr &= ~(SCSCR_TE | SCSCR_RE);
>> + serial_port_out(port, SCSCR, scscr);
>
> Given that the register contains lots of interrupt enable bits, would it make
> sense to just write it to 0 to disable everything ? I don't think we need to
> keep any of the SCSCR bits across shutdown/startup.
I don't know.
Actually this patch causes a problem on e.g. armadillo and kzm9g, where
serial console output suddenly stops on halt/reboot:
| # halt
|
| Broadcast message from root@armadillo (ttySC1) (Tue Aug 25 14:52:35 2015):
| The system is going down for system halt NOW!
| INIT: Switching to runlevel: 0
| INIT: Sending process
After reverting, it continues again with:
| es the TERM signal
| [info] Using makefile-style concurrent boot in runlevel 0.
| [ ok ] Asking all remaining processes to terminate...done.
| [ ok ] All processes ended within 1 seconds...done.
| [ ok ] Stopping enhanced syslogd: rsyslogd.
| [ ok ] Stopping NFS common utilities: idmapd statd.
| rpcbind: rpcbind terminating on signal. Restart with "rpcbind -w"
| [ ok ] Stopping rpcbind daemon....
| [....] not deconfiguring network interfaces: network file systems
still mounted.[war (warning).
| [info] Saving the system clock.
| [info] Hardware Clock updated to Tue Aug 25 14:56:18 CEST 2015.
| [ ok ] Deactivating swap...done.
| [info] Will now halt.
| reboot: System halted
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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