diff options
| author | Joel Stanley <joel@jms.id.au> | 2017-05-02 10:45:42 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-05-18 17:19:16 +0300 |
| commit | ea5244e2af3b4813bf3d90ba6a6481d1a3c33d15 (patch) | |
| tree | fd749101b10ce79c833f5dd8f212039cf32bdd8e | |
| parent | 70b2fe355a4cac3488a208ff13defefef45d6f77 (diff) | |
| download | linux-ea5244e2af3b4813bf3d90ba6a6481d1a3c33d15.tar.xz | |
serial: 8250: Add flag so drivers can avoid THRE probe
The probing of THRE irq behaviour assumes the other end will be reading
bytes out of the buffer in order to probe the port at driver init. In
some cases the other end cannot be relied upon to read these bytes, so
provide a flag for them to skip this step.
Bit 19 was chosen as the flags are a int and the top bits are taken.
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 2 | ||||
| -rw-r--r-- | include/linux/serial_core.h | 1 |
2 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 09a65a3ec7f7..d5b6cee87801 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2229,7 +2229,7 @@ int serial8250_do_startup(struct uart_port *port) } } - if (port->irq) { + if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { unsigned char iir1; /* * Test for UARTs that do not reassert THRE when the diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 64d892f1e5cd..1775500294bb 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -195,6 +195,7 @@ struct uart_port { #define UPF_NO_TXEN_TEST ((__force upf_t) (1 << 15)) #define UPF_MAGIC_MULTIPLIER ((__force upf_t) ASYNC_MAGIC_MULTIPLIER /* 16 */ ) +#define UPF_NO_THRE_TEST ((__force upf_t) (1 << 19)) /* Port has hardware-assisted h/w flow control */ #define UPF_AUTO_CTS ((__force upf_t) (1 << 20)) #define UPF_AUTO_RTS ((__force upf_t) (1 << 21)) |