On Wed, May 18, 2011 at 7:56 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> On Wed, May 18, 2011 at 1:44 AM, Hornung, Michael <mhornung@xxxxxxxxxx> wrote:
>>>> There is an UART (FPGA IP Core) in that system located at address 1900h using interrupt 3. In order to get Kernel messages at boot time,
>>>> I changed file arch/x86/include/asm/serial.h as follows:
>>>>
>>>> - { 0, BASE_BAUD, 0x3F8, 4, STD_COM_FLAGS }, /* ttyS0 */ \
>>>> + { 0, BASE_BAUD, 0x1900, 3, STD_COM_FLAGS }, /* ttyS0 */ \
>>>>
>>>> that is the only change I made to the kernel sources.
>>
>>> Is this UART connected via PCI? I don't think so, because I don't see
>>> any I/O BARs that include 0x1900.
>>
>> The UART is connected via LPC bus.
>
> Makes sense; that's a common way for attaching UARTs, and they are
> normally described via ACPI. When you do that, I think it will show
> up as ttyS4 (be sure you build with CONFIG_SERIAL_8250_PNP=y), so
> you'll have to use "console=ttyS4" when you boot. ttyS0-ttyS3 are
> taken by the hard-coded ports in serial.h, even though they may not
> exist on your platform.
Hi Michael,
Any update on this problem? Did it make any difference to put the
UART in the ACPI namespace?
Bjorn
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