lkml.org 
[lkml]   [2001]   [May]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] drivers/char/serial.c bug in ST16C654 detection
Anyone know where Ted Tso is?  He hasn't posted in several weeks.
Alan, will you put this in -ac? This patch fixes a bug in serial.c
that causes a crash on machines with a ST16C654.

On Tue, May 15, 2001 at 09:52:01AM -0400, Stuart MacDonald wrote:

> Kernel version? Distribution? Are you using a serial console?

2.4.5-pre1 (see patch).

> The revision should always be saved if it's available. Hmm.
> I didn't look carefully yesterday. The DLL always contains the
> revision for the 85x family. Why do you think it doesn't?

Because the comment was ambiguous. I don't have the data sheet for
the 85x family so I just wrote the code according to the comment.
I'll change the comment to make it clear.

> I think your patch below is good, I'm just mystified by this
> kablooey thing.

Thanks. Corrected version of the patch is below.

-VAL

--- linux-2.4.5-pre1/drivers/char/serial.c Thu Apr 19 00:26:34 2001
+++ linux/drivers/char/serial.c Thu May 17 03:12:09 2001
@@ -3507,7 +3507,7 @@
struct serial_state *state,
unsigned long flags)
{
- unsigned char scratch, scratch2, scratch3;
+ unsigned char scratch, scratch2, scratch3, scratch4;

/*
* First we check to see if it's an Oxford Semiconductor UART.
@@ -3548,20 +3548,33 @@
* then reading back DLL and DLM. If DLM reads back 0x10,
* then the UART is a XR16C850 and the DLL contains the chip
* revision. If DLM reads back 0x14, then the UART is a
- * XR16C854.
- *
+ * XR16C854 and the DLL contains the chip revision.
*/
+
+ /* Save the DLL and DLM */
+
serial_outp(info, UART_LCR, UART_LCR_DLAB);
+ scratch3 = serial_inp(info, UART_DLL);
+ scratch4 = serial_inp(info, UART_DLM);
+
serial_outp(info, UART_DLL, 0);
serial_outp(info, UART_DLM, 0);
- state->revision = serial_inp(info, UART_DLL);
+ scratch2 = serial_inp(info, UART_DLL);
scratch = serial_inp(info, UART_DLM);
serial_outp(info, UART_LCR, 0);
+
if (scratch == 0x10 || scratch == 0x14) {
+ state->revision = scratch2;
state->type = PORT_16850;
return;
}

+ /* Restore the DLL and DLM */
+
+ serial_outp(info, UART_LCR, UART_LCR_DLAB);
+ serial_outp(info, UART_DLL, scratch3);
+ serial_outp(info, UART_DLM, scratch4);
+ serial_outp(info, UART_LCR, 0);
/*
* We distinguish between the '654 and the '650 by counting
* how many bytes are in the FIFO. I'm using this for now,

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:53    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site