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authorJohan Hovold <johan@kernel.org>2021-04-21 11:54:55 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-04-22 12:09:25 +0200
commit46a2675e8f0d9c5da85b608ceb573f425432a6e7 (patch)
treeb4401fc0ff997af9e536399ab3eddd4a1a3a731f /drivers/tty
parent4eec66e4b2a03a4c495f646d4cd98a655b4d9176 (diff)
serial: lpc32xx_hs: drop low-latency workaround
Commit ec128510905c ("tty: serial: lpc32xx_hs: drop uart_port->lock before calling tty_flip_buffer_push()") claimed to address a locking issue but only provided a dubious lockdep splat from an unrelated driver, which in the end turned out to be due a broken local change carried by the author. Unfortunately these patches were merged before the issue had been analysed properly so the commit messages makes no sense whatsoever. The real issue was first seen on RT which at the time effectively always set the low_latency flag for all serial drivers by patching tty_flip_buffer_push(). This in turn revealed that many drivers did not handle the infamous low_latency behaviour which meant that data was pushed immediately to the line discipline instead of being deferred to a work queue. Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"), tty_flip_buffer_push() always schedules a work item to push data to the line discipline and there's no need to keep any low_latency hacks around. Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/ Signed-off-by: Johan Hovold <johan@kernel.org> Link: https://lore.kernel.org/r/20210421095509.3024-13-johan@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/lpc32xx_hs.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index 1fa098d7aec4..b199d7859961 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -273,9 +273,7 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
tmp = readl(LPC32XX_HSUART_FIFO(port->membase));
}
- spin_unlock(&port->lock);
tty_flip_buffer_push(tport);
- spin_lock(&port->lock);
}
static void __serial_lpc32xx_tx(struct uart_port *port)