brcm2708: rename target to bcm27xx

[openwrt/openwrt.git] / target / linux / brcm2708 / patches-4.19 / 950-0807-tty-amba-pl011-Avoid-rare-write-when-full-error.patch

diff --git a/target/linux/brcm2708/patches-4.19/950-0807-tty-amba-pl011-Avoid-rare-write-when-full-error.patch b/target/linux/brcm2708/patches-4.19/950-0807-tty-amba-pl011-Avoid-rare-write-when-full-error.patch
deleted file mode 100644 (file)
index 8deb882..0000000
--- a/target/linux/brcm2708/patches-4.19/950-0807-tty-amba-pl011-Avoid-rare-write-when-full-error.patch
+++ /dev/null
@@ -1,42 +0,0 @@
-From 8ef5143f743a4e922fdf0029f81452d3d7003daf Mon Sep 17 00:00:00 2001
-From: Phil Elwell <phil@raspberrypi.org>
-Date: Wed, 29 Jan 2020 09:35:19 +0000
-Subject: [PATCH] tty: amba-pl011: Avoid rare write-when-full error
-
-Under some circumstances on BCM283x processors data loss can be
-observed - a single byte missing from the TX output stream. These bytes
-are always the last byte of a batch of 8 written from pl011_tx_chars
-when from_irq is true, meaning that the FIFO full flag is not checked
-before writing.
-
-The transmit optimisation relies on the FIFO being half-empty when the
-TX interrupt is raised. Instrumenting the driver further showed that
-the failure case correlated with the TX FIFO full flag being set at the
-point where the last byte was written to the data register, which
-explains the data loss but not how the FIFO appeared to be prematurely
-full. A possible explanation is that a FIFO write was in flight at the
-time the interrupt was raised, but as yet there is no hypothesis as to
-how this might occur.
-
-In the absence of a clear understanding of the failure mechanism, avoid
-the problem by checking the FIFO levels before writing the last byte of
-the group, which will have minimal performance impact.
-
-Signed-off-by: Phil Elwell <phil@raspberrypi.org>
----
- drivers/tty/serial/amba-pl011.c | 4 ++++
- 1 file changed, 4 insertions(+)
-
---- a/drivers/tty/serial/amba-pl011.c
-+++ b/drivers/tty/serial/amba-pl011.c
-@@ -1444,6 +1444,10 @@ static bool pl011_tx_chars(struct uart_a
-               if (likely(from_irq) && count-- == 0)
-                       break;
- 
-+              if (likely(from_irq) && count == 0 &&
-+                  pl011_read(uap, REG_FR) & UART01x_FR_TXFF)
-+                      break;
-+
-               if (!pl011_tx_char(uap, xmit->buf[xmit->tail], from_irq))
-                       break;
-