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    SubjectRe: Bogus serial port ttyS02
    On Wed, 13 Aug 2003, Geert Uytterhoeven wrote:
    > On Wed, 13 Aug 2003, Russell King wrote:
    > > You could enable DEBUG_AUTOCONF in 8250.c in 2.6.0-test3 and give
    > > further probing information. 8)

    This patch kills a warning if DEBUG_AUTOCONF is enabled:

    --- linux-ppc-2.6.0-test3/drivers/serial/8250.c Mon Aug 11 02:20:41 2003
    +++ linux-longtrail-2.6.0-test3/drivers/serial/8250.c Wed Aug 13 22:31:07 2003
    @@ -557,7 +557,7 @@
    if (!up->port.iobase && !up->port.mapbase && !up->port.membase)
    return;

    - DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04x, 0x%08lx): ",
    + DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04x, %p): ",
    up->port.line, up->port.iobase, up->port.membase);

    /*
    > > Looking at PPC's pc_serial.h, it seems that you've told it to probe
    > > there using ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ.
    > > ASYNC_SKIP_TEST means that we use a reduced test to probe for a port -
    > > we just check that we can read back a value written to 0x3e9. If this
    > > suceeds, we decide that there is a port present, and go on to try and
    > > derive its type.
    > >
    > > If you want to enable the more rigorous tests, remove ASYNC_SKIP_TEST
    > > from the port flags. This will make us check that the device behaves
    > > like a UART before deciding that it is one.
    >
    > If I remove the ASYNC_SKIP_TEST flag, I get
    >
    > ttyS2: autoconf (0x03e8, 00000000): LOOP test failed (10) type=unknown
    >
    > and only the 2 existing ports are detected! Thanks!
    >
    > Why is the ASYNC_SKIP_TEST flag needed? Would it be safe to remove it for PPC,
    > or are there possible side effects?

    This patch removes the ASYNC_SKIP_TEST flag on PPC:

    --- linux-ppc-2.6.0-test3/include/asm-ppc/pc_serial.h Mon Aug 11 02:21:00 2003
    +++ linux-longtrail-2.6.0-test3/include/asm-ppc/pc_serial.h Wed Aug 13 23:01:50 2003
    @@ -28,10 +28,10 @@

    /* Standard COM flags (except for COM4, because of the 8514 problem) */
    #ifdef CONFIG_SERIAL_DETECT_IRQ
    -#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ)
    +#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_AUTO_IRQ)
    #define STD_COM4_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_AUTO_IRQ)
    #else
    -#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)
    +#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF)
    #define STD_COM4_FLAGS ASYNC_BOOT_AUTOCONF
    #endif

    OK to apply?
    Gr{oetje,eeting}s,
    Geert

    --
    Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

    In personal conversations with technical people, I call myself a hacker. But
    when I'm talking to journalists I just say "programmer" or something like that.
    -- Linus Torvalds

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