From: Sergey Organov <sorganov@gmail.com>
To: linux-serial@vger.kernel.org
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Sascha Hauer" <s.hauer@pengutronix.de>,
"Sergey Organov" <sorganov@gmail.com>,
"NXP Linux Team" <linux-imx@nxp.com>,
"Pengutronix Kernel Team" <kernel@pengutronix.de>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/5] serial: imx: get rid of unbounded busy-waiting loop
Date: Wed, 28 Aug 2019 21:37:51 +0300 [thread overview]
Message-ID: <1567017475-11919-2-git-send-email-sorganov@gmail.com> (raw)
In-Reply-To: <1567017475-11919-1-git-send-email-sorganov@gmail.com>
imx_set_termios(): remove busy-waiting "drain Tx FIFO" loop. Worse
yet, it was potentially unbounded wait due to RTS/CTS (hardware)
handshake.
Let user space ensure draining is done before termios change, if
draining is needed in the first place.
Signed-off-by: Sergey Organov <sorganov@gmail.com>
---
drivers/tty/serial/imx.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index d9a73c7..47b6156 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1644,7 +1644,7 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
uart_update_timeout(port, termios->c_cflag, baud);
/*
- * disable interrupts and drain transmitter
+ * disable interrupts
*/
old_ucr1 = imx_uart_readl(sport, UCR1);
imx_uart_writel(sport,
@@ -1652,9 +1652,6 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
UCR1);
imx_uart_writel(sport, old_ucr2 & ~UCR2_ATEN, UCR2);
- while (!(imx_uart_readl(sport, USR2) & USR2_TXDC))
- barrier();
-
/* then, disable everything */
imx_uart_writel(sport, old_ucr2 & ~(UCR2_TXEN | UCR2_RXEN | UCR2_ATEN), UCR2);
--
2.10.0.1.g57b01a3
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-08-28 18:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190530152950.25377-1-sorganov@gmail.com>
2019-08-28 18:37 ` [PATCH v2 0/5] Serial: imx: various fixes Sergey Organov
2019-08-28 18:37 ` Sergey Organov [this message]
2019-08-28 18:37 ` [PATCH v2 2/5] serial: imx: do not stop Rx/Tx on termios change Sergey Organov
2019-08-28 18:37 ` [PATCH v2 3/5] serial: imx: do not disable individual irqs during " Sergey Organov
2019-08-28 18:37 ` [PATCH v2 4/5] serial: imx: fix data breakage on " Sergey Organov
2019-08-28 18:37 ` [PATCH v2 5/5] serial: imx: use Tx ready rather than Tx empty irq Sergey Organov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1567017475-11919-2-git-send-email-sorganov@gmail.com \
--to=sorganov@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=kernel@pengutronix.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-imx@nxp.com \
--cc=linux-serial@vger.kernel.org \
--cc=s.hauer@pengutronix.de \
--cc=u.kleine-koenig@pengutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox