Date: Tue, 28 Nov 2006 21:20:20 GMT From: Marcel Moolenaar <xcllnt@mac.com> To: freebsd-i386@FreeBSD.org Subject: Re: i386/105616: UART PCI device just silent... Message-ID: <200611282120.kASLKKow008043@freefall.freebsd.org>
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The following reply was made to PR i386/105616; it has been noted by GNATS.
From: Marcel Moolenaar <xcllnt@mac.com>
To: puc-uart@oldach.net (Helge Oldach)
Cc: FreeBSD-gnats-submit@FreeBSD.org
Subject: Re: i386/105616: UART PCI device just silent...
Date: Tue, 28 Nov 2006 13:09:19 -0800
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On Nov 28, 2006, at 12:49 PM, Helge Oldach wrote:
> Hi Marcel,
>
> one more observation:
>
> When I connect the two puc uart ports at different speeds,
> communication
> still works fine. It even works with 50 against 115200 bps, in either
> direction! Even piping files to remote works without visible errors.
>
> Further, if I place both sides at 50 bps (via "cu -s 50"),
> communication
> is definitely much faster than one would expect at 50 bps. And it
> doesn't seem to change when both ends are at 115200. I'd say the
> actual
> speed is somewhere around 9600.
>
> It seems that setting clock rate on this board does not work properly,
> but instead some default non-standard value remains set forever...
Interesting. The uart(4) driver in -STABLE writes the baudrate in a
single 16-bit wide operation. The uart(4) driver in -CURRENT doesn't
do that. Could you try the attached patch?
thanks!
--
Marcel Moolenaar
xcllnt@mac.com
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Index: ic/ns16550.h
===================================================================
RCS file: /home/ncvs/src/sys/dev/ic/ns16550.h,v
retrieving revision 1.16
diff -u -r1.16 ns16550.h
--- ic/ns16550.h 20 Nov 2004 23:19:42 -0000 1.16
+++ ic/ns16550.h 28 Nov 2006 21:06:52 -0000
@@ -127,7 +127,8 @@
#define com_dlbl com_dll
#define com_dlm 1 /* divisor latch high (R/W) */
#define com_dlbh com_dlm
-#define REG_DL com_dll
+#define REG_DLL com_dll
+#define REG_DLH com_dlm
/* 16450 register #7. Not multiplexed. */
#define com_scr 7 /* scratch register (R/W) */
Index: uart/uart.h
===================================================================
RCS file: /home/ncvs/src/sys/dev/uart/uart.h,v
retrieving revision 1.4
diff -u -r1.4 uart.h
--- uart/uart.h 6 Jan 2005 01:43:26 -0000 1.4
+++ uart/uart.h 28 Nov 2006 21:05:06 -0000
@@ -50,12 +50,6 @@
#define uart_setreg(bas, reg, value) \
bus_space_write_1((bas)->bst, (bas)->bsh, uart_regofs(bas, reg), value)
-/* 16-bit I/O (e.g. to divisor latch) */
-#define uart_getdreg(bas, reg) \
- bus_space_read_2((bas)->bst, (bas)->bsh, uart_regofs(bas, reg))
-#define uart_setdreg(bas, reg, value) \
- bus_space_write_2((bas)->bst, (bas)->bsh, uart_regofs(bas, reg), value)
-
/*
* XXX we don't know the length of the bus space address range in use by
* the UART. Since barriers don't use the length field currently, we put
Index: uart/uart_dev_ns8250.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/uart/uart_dev_ns8250.c,v
retrieving revision 1.14
diff -u -r1.14 uart_dev_ns8250.c
--- uart/uart_dev_ns8250.c 6 Jan 2005 01:43:26 -0000 1.14
+++ uart/uart_dev_ns8250.c 28 Nov 2006 21:04:48 -0000
@@ -75,7 +75,7 @@
lcr = uart_getreg(bas, REG_LCR);
uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
uart_barrier(bas);
- divisor = uart_getdreg(bas, REG_DL);
+ divisor = uart_getreg(bas, REG_DLL) | (uart_getreg(bas, REG_DLH) << 8);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
@@ -194,12 +194,13 @@
/* Set baudrate. */
if (baudrate > 0) {
- uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
- uart_barrier(bas);
divisor = ns8250_divisor(bas->rclk, baudrate);
if (divisor == 0)
return (EINVAL);
- uart_setdreg(bas, REG_DL, divisor);
+ uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
+ uart_barrier(bas);
+ uart_setreg(bas, REG_DLL, divisor & 0xff);
+ uart_setreg(bas, REG_DLH, (divisor >> 8) & 0xff);
uart_barrier(bas);
}
@@ -519,7 +520,8 @@
lcr = uart_getreg(bas, REG_LCR);
uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
uart_barrier(bas);
- divisor = uart_getdreg(bas, REG_DL);
+ divisor = uart_getreg(bas, REG_DLL) |
+ (uart_getreg(bas, REG_DLH) << 8);
uart_barrier(bas);
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
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