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Groups > linux.kernel > #1616558
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| From | Joel Stanley <joel@jms.id.au> |
| Newsgroups | linux.kernel |
| Subject | [PATCH v2 1/2] serial: 8250: Add flag so drivers can avoid THRE probe |
| Date | Wed, 05 Apr 2017 06:10:01 +0200 |
| Message-ID | <tsKqB-62k-3@gated-at.bofh.it> (permalink) |
| References | <tsKqB-62k-1@gated-at.bofh.it> |
| X-Original-To | Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.com>, Mark Rutland <mark.rutland@arm.com>, Rob Herring <robh+dt@kernel.org> |
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| X-Original-Cc | linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Andy Shevchenko <andy.shevchenko@gmail.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Jeremy Kerr <jk@ozlabs.org>, openbmc@lists.ozlabs.org |
| X-Original-Date | Wed, 5 Apr 2017 13:33:51 +0930 |
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| Xref | csiph.com linux.kernel:1616558 |
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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 16 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>
---
drivers/tty/serial/8250/8250_port.c | 2 +-
include/linux/serial_core.h | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 6119516ef5fc..60a6c247340f 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 58484fb35cc8..260245deec94 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))
--
2.11.0
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[PATCH v2 0/2] drivers: serial: Aspeed VUART driver Joel Stanley <joel@jms.id.au> - 2017-04-05 06:10 +0200
[PATCH v2 1/2] serial: 8250: Add flag so drivers can avoid THRE probe Joel Stanley <joel@jms.id.au> - 2017-04-05 06:10 +0200
Re: [PATCH v2 1/2] serial: 8250: Add flag so drivers can avoid THRE probe Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-04-05 12:40 +0200
[PATCH v2 2/2] drivers/serial: Add driver for Aspeed virtual UART Joel Stanley <joel@jms.id.au> - 2017-04-05 06:10 +0200
Re: [PATCH v2 2/2] drivers/serial: Add driver for Aspeed virtual UART Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-04-05 13:00 +0200
Re: [PATCH v2 2/2] drivers/serial: Add driver for Aspeed virtual UART Joel Stanley <joel@jms.id.au> - 2017-04-10 05:10 +0200
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