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    [W:0.023 / U:37.036 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site