diff options
| -rw-r--r-- | target/linux/ar71xx/patches-3.6/004-tty-serial-ar933x_uart-fix-baud-rate-calculation.patch (renamed from target/linux/ar71xx/patches-3.6/211-ar933x_uart-improve-serial-clock-calculation.patch) | 62 |
1 files changed, 60 insertions, 2 deletions
diff --git a/target/linux/ar71xx/patches-3.6/211-ar933x_uart-improve-serial-clock-calculation.patch b/target/linux/ar71xx/patches-3.6/004-tty-serial-ar933x_uart-fix-baud-rate-calculation.patch index 510b75ed0f..44eebabb18 100644 --- a/target/linux/ar71xx/patches-3.6/211-ar933x_uart-improve-serial-clock-calculation.patch +++ b/target/linux/ar71xx/patches-3.6/004-tty-serial-ar933x_uart-fix-baud-rate-calculation.patch @@ -1,3 +1,61 @@ +From 2dff8ad92661b6c99e9ba8b5918e43b522551556 Mon Sep 17 00:00:00 2001 +From: Gabor Juhos <juhosg@openwrt.org> +Date: Wed, 14 Nov 2012 10:38:13 +0100 +Subject: [PATCH] tty/serial/ar933x_uart: fix baud rate calculation + +commit 2dff8ad92661b6c99e9ba8b5918e43b522551556 upstream. + +The UART of the AR933x SoC implements a fractional divisor +for generating the desired baud rate. + +The current code uses a fixed value for the fractional +part of the divisor, and this leads to improperly +calculated baud rates: + + baud scale step real baud diff + 300 5207* 8192 17756 17456 5818.66% + 600 2603* 8192 35511 34911 5818.50% + 1200 1301* 8192 71023 69823 5818.58% + 2400 650* 8192 11241 8841 368.37% + 4800 324* 8192 22645 17845 371.77% + 9600 161 8192 9645 45 0.46% + 14400 107 8192 14468 68 0.47% + 19200 80 8192 19290 90 0.46% + 28800 53 8192 28935 135 0.46% + 38400 39 8192 39063 663 1.72% + 57600 26 8192 57870 270 0.46% + 115200 12 8192 120192 4992 4.33% + 230400 5 8192 260417 30017 13.02% + 460800 2 8192 520833 60033 13.02% + 921600 0 8192 1562500 640900 69.93% + +After the patch, the integer and fractional parts of the +divisor will be calculated dynamically. This ensures that +the UART will use correct baud rates: + + baud scale step real baud diff + 300 6 11 300 0 0.00% + 600 54 173 600 0 0.00% + 1200 30 195 1200 0 0.00% + 2400 30 390 2400 0 0.00% + 4800 48 1233 4800 0 0.00% + 9600 78 3976 9600 0 0.00% + 14400 98 7474 14400 0 0.00% + 19200 55 5637 19200 0 0.00% + 28800 130 19780 28800 0 0.00% + 38400 36 7449 38400 0 0.00% + 57600 78 23857 57600 0 0.00% + 115200 43 26575 115200 0 0.00% + 230400 23 28991 230400 0 0.00% + 460800 11 28991 460800 0 0.00% + 921600 5 28991 921599 -1 0.00% + +Signed-off-by: Gabor Juhos <juhosg@openwrt.org> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + drivers/tty/serial/ar933x_uart.c | 90 +++++++++++++++++++++++++++++++++++--- + 1 file changed, 85 insertions(+), 5 deletions(-) + --- a/drivers/tty/serial/ar933x_uart.c +++ b/drivers/tty/serial/ar933x_uart.c @@ -25,11 +25,19 @@ @@ -133,8 +191,8 @@ + /* reenable the UART */ + ar933x_uart_rmw(up, AR933X_UART_CS_REG, -+ AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S, -+ AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S); ++ AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S, ++ AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S); + spin_unlock_irqrestore(&up->port.lock, flags); |