[MinnowBoard] UART ports configuration issues

[Berth-Olof Bergman]

There are only one low speed UART on Minnowboard. The high speed  UARTs are not compatible with the low speed UART. They are memory mapped devices using DMA transfer. The BIOS or OS may emulate the 16550 UART, trapping access to legacy UART I/O addresses. That requires the high speed UART base clock to be set to 1.8432 MHz, so the legacy UART baud rates can be established.

The high speed UARTs are probably not emulated by your BIOS, due to your problems. I recommend you use a native driver for the high speed UARTs.

   
> 1 jun 2015 kl. 23:27 skrev Orozco, Edgar Alexis <edgar.alexis.orozco at delphi.com>:
> 
> Hello...
> 
> When I try to read or write to the ports ttyS1 or ttyS2, I get an input/output error.
> 
> That's basically it.
> 
> 
> -----Original Message-----
> From: elinux-MinnowBoard [mailto:elinux-minnowboard-bounces at lists.elinux.org] On Behalf Of John Hawley
> Sent: lunes, 01 de junio de 2015 04:25 p.m.
> To: elinux-minnowboard at lists.elinux.org
> Subject: Re: [MinnowBoard] UART ports configuration issues
> 
> On 06/01/2015 12:42 PM, Orozco, Edgar Alexis wrote:
>> Hello everybody!
>> 
>> 
>> 
>> I am experiencing an issue with UART ports: here's the output of
>> setserial -ag /dev/ttyS*
>> 
>> 
>> 
>> /dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
>> 
>>                Baud_base: 115200, close_delay: 50, divisor: 0
>> 
>>                closing_wait: 3000
>> 
>>                Flags: spd_normal skip_test auto_irq
>> 
>> 
>> 
>> /dev/ttyS1, Line 1, UART: unknown, Port: 0x02f8, IRQ: 3
>> 
>>                Baud_base: 115200, close_delay: 50, divisor: 0
>> 
>>                closing_wait: 3000
>> 
>>                Flags: spd_normal skip_test auto_irq
>> 
>> 
>> 
>> /dev/ttyS2, Line 2, UART: unknown, Port: 0x03e8, IRQ: 4
>> 
>>                Baud_base: 115200, close_delay: 50, divisor: 0
>> 
>>                closing_wait: 3000
>> 
>>                Flags: spd_normal skip_test auto_irq
>> 
>> 
>> 
>> /dev/ttyS3, Line 3, UART: unknown, Port: 0x02e8, IRQ: 3
>> 
>>                Baud_base: 115200, close_delay: 50, divisor: 0
>> 
>>                closing_wait: 3000
>> 
>>                Flags: spd_normal auto_irq
>> 
>> 
>> 
>> ttyS0 is working OK since I am using it as a serial console.
>> 
>> I noticed that the dmesg output was commonly showing "ttySX MMIO at
>> 0x<address>". Not anymore!.
>> 
>> I thought it was related to a BIOS configuration (just like Intel
>> NUC's)... but I was not able to find something related to it.
>> 
>> 
>> 
>> Any thoughts ?
>> 
>> Thank you very much!
> 
> Can you just copy paste what it was showing exactly, it's not really clear to me what the problem is or what the error message that's getting reported is...
> 
> - John 'Warthog9' Hawley
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