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SubjectRe: [PATCH-next 3/3] serial/sysrq: Add MAGIC_SYSRQ_SERIAL_SEQUENCE
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Hi Joe,

On 1/10/20 4:50 PM, Joe Perches wrote:
> On Thu, 2020-01-09 at 21:54 +0000, Dmitry Safonov wrote:
>> Many embedded boards have a disconnected TTL level serial which can
>> generate some garbage that can lead to spurious false sysrq detects.
>
> trivia:
>
>> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> []
>> @@ -3081,6 +3081,38 @@ void uart_insert_char(struct uart_port *port, unsigned int status,
> []
>> +const char sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
>
> static const?

Will do, thanks!

>
>> +static int uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
>
> This function return might read better as bool not int

Yeah, no hard feelings, will convert.

[..]
>> @@ -243,10 +243,10 @@ struct uart_port {
>> unsigned long sysrq; /* sysrq timeout */
>> unsigned int sysrq_ch; /* char for sysrq */
>> unsigned char has_sysrq;
>> + unsigned char sysrq_seq; /* index in sysrq_toggle_seq */
>
> unsigned int?
>
> Or maybe set a maximum length of MAGIC_SYSRQ_SERIAL_SEQUENCE.

I think, 256 chars should be enough to send on serial (c)

I'm not aware of a way to put the max string length in Kconfig, so I did
in the patch:
BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >=
sizeof(port->sysrq_seq)*U8_MAX);

Do you have something more elegant in your mind?

Thanks,
Dmitry

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