This is a note to let you know that I've just added the patch titled
MIPS: ath79: make bootconsole wait for both THRE and TEMT
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-ath79-make-bootconsole-wait-for-both-thre-and-temt.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f5b556c94c8490d42fea79d7b4ae0ecbc291e69d Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 24 Mar 2016 16:02:52 +0100
Subject: MIPS: ath79: make bootconsole wait for both THRE and TEMT
From: Matthias Schiffer <mschiffer@xxxxxxxxxxxxxxxxxxxx>
commit f5b556c94c8490d42fea79d7b4ae0ecbc291e69d upstream.
This makes the ath79 bootconsole behave the same way as the generic 8250
bootconsole.
Also waiting for TEMT (transmit buffer is empty) instead of just THRE
(transmit buffer is not full) ensures that all characters have been
transmitted before the real serial driver starts reconfiguring the serial
controller (which would sometimes result in garbage being transmitted.)
This change does not cause a visible performance loss.
In addition, this seems to fix a hang observed in certain configurations on
many AR7xxx/AR9xxx SoCs during autoconfig of the real serial driver.
A more complete follow-up patch will disable 8250 autoconfig for ath79
altogether (the serial controller is detected as a 16550A, which is not
fully compatible with the ath79 serial, and the autoconfig may lead to
undefined behavior on ath79.)
Signed-off-by: Matthias Schiffer <mschiffer@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/mips/ath79/early_printk.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/mips/ath79/early_printk.c
+++ b/arch/mips/ath79/early_printk.c
@@ -31,13 +31,15 @@ static inline void prom_putchar_wait(voi
} while (1);
}
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
static void prom_putchar_ar71xx(unsigned char ch)
{
void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
- prom_putchar_wait(base + UART_LSR * 4, UART_LSR_THRE, UART_LSR_THRE);
+ prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
__raw_writel(ch, base + UART_TX * 4);
- prom_putchar_wait(base + UART_LSR * 4, UART_LSR_THRE, UART_LSR_THRE);
+ prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
}
static void prom_putchar_ar933x(unsigned char ch)
Patches currently in stable-queue which might be from mschiffer@xxxxxxxxxxxxxxxxxxxx are
queue-4.4/mips-ath79-make-bootconsole-wait-for-both-thre-and-temt.patch
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