[U-Boot] [PATCH 0/3] Collection of ns16550 UART driver refactoring
Masahiro Yamada (3): serial: ns16550: drop CONFIG_OMAP1610 from the special case serial: ns16550: use DIV_ROUND_CLOSEST macro to compute the divisor serial: ns16550: use a const variable instead of macro
drivers/serial/serial_ns16550.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-)
If CONFIG_OMAP1610 is defined, the code returning the fixed value (26) is enabled. But this case is covered by the following code.
(CONFIG_SYS_NS16550_CLK + (gd->baudrate * (MODE_X_DIV / 2))) / (MODE_X_DIV * gd->baudrate) = (48000000 + (115200 * (16 / 2))) / (16 * 115200) = 48921600 / 1843200 = 26
The "#ifdef CONFIG_OMAP1610" was added by commit 6f21347d more than ten years ago. In those days, the divide-and-round was not used. I guess that is why this weird code was added here.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com Cc: Tom Rini trini@ti.com Cc: Rishi Bhattacharya rishi@ti.com ---
drivers/serial/serial_ns16550.c | 6 ------ 1 file changed, 6 deletions(-)
diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c index ba68d46..056ef2a 100644 --- a/drivers/serial/serial_ns16550.c +++ b/drivers/serial/serial_ns16550.c @@ -128,12 +128,6 @@ static int calc_divisor (NS16550_t port) } port->osc_12m_sel = 0; /* clear if previsouly set */ #endif -#ifdef CONFIG_OMAP1610 - /* If can't cleanly clock 115200 set div to 1 */ - if ((CONFIG_SYS_NS16550_CLK == 48000000) && (gd->baudrate == 115200)) { - return (26); /* return 26 for base divisor */ - } -#endif
#define MODE_X_DIV 16 /* Compute divisor value. Normally, we should simply return:
Hi Tom,
On Fri, 11 Jul 2014 20:29:02 +0900 Masahiro Yamada yamada.m@jp.panasonic.com wrote:
If CONFIG_OMAP1610 is defined, the code returning the fixed value (26) is enabled. But this case is covered by the following code.
(CONFIG_SYS_NS16550_CLK + (gd->baudrate * (MODE_X_DIV / 2))) / (MODE_X_DIV * gd->baudrate) = (48000000 + (115200 * (16 / 2))) / (16 * 115200) = 48921600 / 1843200 = 26
The "#ifdef CONFIG_OMAP1610" was added by commit 6f21347d more than ten years ago. In those days, the divide-and-round was not used. I guess that is why this weird code was added here.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com Cc: Tom Rini trini@ti.com Cc: Rishi Bhattacharya rishi@ti.com
The mail to "Rishi Bhattacharya rishi@ti.com" has been bouncing.
Could you assign a new maintainer for omap5912osk board? Or is this already a dead board?
Best Regards Masahiro Yamada
On Fri, Jul 11, 2014 at 08:29:02PM +0900, Masahiro Yamada wrote:
If CONFIG_OMAP1610 is defined, the code returning the fixed value (26) is enabled. But this case is covered by the following code.
(CONFIG_SYS_NS16550_CLK + (gd->baudrate * (MODE_X_DIV / 2))) / (MODE_X_DIV * gd->baudrate) = (48000000 + (115200 * (16 / 2))) / (16 * 115200) = 48921600 / 1843200 = 26
The "#ifdef CONFIG_OMAP1610" was added by commit 6f21347d more than ten years ago. In those days, the divide-and-round was not used. I guess that is why this weird code was added here.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com Cc: Tom Rini trini@ti.com Cc: Rishi Bhattacharya rishi@ti.com
Applied to u-boot/master, thanks!
The function still returns the same value.
The comment block is no longer necessary because our intention is clear enough by using DIV_ROUND_CLOSEST() macro.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com ---
drivers/serial/serial_ns16550.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c index 056ef2a..49e2c1f 100644 --- a/drivers/serial/serial_ns16550.c +++ b/drivers/serial/serial_ns16550.c @@ -130,13 +130,9 @@ static int calc_divisor (NS16550_t port) #endif
#define MODE_X_DIV 16 - /* Compute divisor value. Normally, we should simply return: - * CONFIG_SYS_NS16550_CLK) / MODE_X_DIV / gd->baudrate - * but we need to round that value by adding 0.5. - * Rounding is especially important at high baud rates. - */ - return (CONFIG_SYS_NS16550_CLK + (gd->baudrate * (MODE_X_DIV / 2))) / - (MODE_X_DIV * gd->baudrate); + + return DIV_ROUND_CLOSEST(CONFIG_SYS_NS16550_CLK, + MODE_X_DIV * gd->baudrate); }
void
On Fri, Jul 11, 2014 at 08:29:03PM +0900, Masahiro Yamada wrote:
The function still returns the same value.
The comment block is no longer necessary because our intention is clear enough by using DIV_ROUND_CLOSEST() macro.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com
Applied to u-boot/master, thanks!
Just for type checking.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com Cc: Marek Vasut marex@denx.de ---
drivers/serial/serial_ns16550.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c index 49e2c1f..4413e69 100644 --- a/drivers/serial/serial_ns16550.c +++ b/drivers/serial/serial_ns16550.c @@ -120,6 +120,8 @@ static NS16550_t serial_ports[6] = {
static int calc_divisor (NS16550_t port) { + const unsigned int mode_x_div = 16; + #ifdef CONFIG_OMAP1510 /* If can't cleanly clock 115200 set div to 1 */ if ((CONFIG_SYS_NS16550_CLK == 12000000) && (gd->baudrate == 115200)) { @@ -129,10 +131,8 @@ static int calc_divisor (NS16550_t port) port->osc_12m_sel = 0; /* clear if previsouly set */ #endif
-#define MODE_X_DIV 16 - return DIV_ROUND_CLOSEST(CONFIG_SYS_NS16550_CLK, - MODE_X_DIV * gd->baudrate); + mode_x_div * gd->baudrate); }
void
On Friday, July 11, 2014 at 01:29:04 PM, Masahiro Yamada wrote:
Just for type checking.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com Cc: Marek Vasut marex@denx.de
Acked-by: Marek Vasut marex@denx.de
Thanks !
Best regards, Marek Vasut
On Fri, Jul 11, 2014 at 08:29:04PM +0900, Masahiro Yamada wrote:
Just for type checking.
Signed-off-by: Masahiro Yamada yamada.m@jp.panasonic.com Cc: Marek Vasut marex@denx.de Acked-by: Marek Vasut marex@denx.de
Applied to u-boot/master, thanks!
participants (3)
-
Marek Vasut -
Masahiro Yamada -
Tom Rini