[Bugme-new] [Bug 40612] New: UART not automatically enabled

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=40612

               URL: https://lkml.org/lkml/2011/7/28/27
           Summary: UART not automatically enabled
           Product: ACPI
           Version: 2.5
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Config-Other
        AssignedTo: acpi_config-other at kernel-bugs.osdl.org
        ReportedBy: bhelgaas at google.com
                CC: jeff.chua.linux at gmail.com
        Regression: No


Jeff says:

> I'm trying to access the serial port ttyS2 that is set in the BIOS as
> "OS Controlled" without much success. If it's set it to "Always
> Enabled",  I can access the serial port.

> This is on the Intermec CV60, and ttyS2 is the touchscreen port.

> # setserial /dev/ttyS2
> /dev/ttyS2, UART: 16550A, Port: 0x03e8, IRQ: 6


> If I set the BIOS to "OS Controlled", I can't access the serial port
> no matter what parameter I pass to the setserial. The factory default
> is "OS Controlled", and Window XP can detect and access the port.

and found that this is enough to enable it:

> echo "auto" > /sys/bus/pnp/devices/00:0a/resources

My guess (with no evidence) is that running _SRS enables the device, and that
Windows does that automatically but Linux doesn't.

I think it's a bug that Linux doesn't make this port work automatically.

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