Re: Mini UART support for Raspberry Pi CM3 ?

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello,

On 6/4/20 12:14 AM, john@mobius-embedded-systems.co.uk wrote:
> Hi Ahmad
> 
> I got a little further and although there's still no serial output on UART1, I at least now see an error message about it (on UART0 still).  
> 
> ns16550_serial 3f215040.serial@7e215040.of: probe failed: Device or resource busy
Drivers request the MMIO region they want to work with. Try the iomem command to see
if the EBUSY is due to a resource clash on 0x7e215040. Although I wonder how that
came about. Normally, with device tree, this shouldn't happen unless the device
tree is faulty.
> So your point about setting CONSOLE_ACTIVATE_NONE was correct 😊.  Maybe I've missed something in the device trees, but am at least heartened to see something printed.  

Can't take credit, because I don't know why this would cause an error message to be
printed, when none was printed before.

Keep us posted.

Cheers
Ahmad

> 
> Thanks
> 
> John
> 
> -----Original Message-----
> From: barebox <barebox-bounces@lists.infradead.org> On Behalf Of Ahmad Fatoum
> Sent: 02 June 2020 11:12
> To: john@mobius-embedded-systems.co.uk <andrew@mobius-embedded-systems.co.uk>; barebox@lists.infradead.org
> Subject: Re: Mini UART support for Raspberry Pi CM3 ?
> 
> On 6/2/20 11:57 AM, john@mobius-embedded-systems.co.uk wrote:
>> Hi Ahmad
>>
>> I have been using v2020.05 but I believe I had enabled all consoles so 
>> I'll try setting it to none and see how that goes.
> 
> This will only fix the use of UART0 as output. To use UART1, you'll need to set stdout-path = &uart1 like ab76f9d09d3b ("ARM: rpi: choose miniuart as
> stdout") does.
> 
> Cheers
> Ahmad
> 
>>
>> Thanks
>>
>> John
>>
>> -----Original Message-----
>> From: barebox <barebox-bounces@lists.infradead.org> On Behalf Of Ahmad 
>> Fatoum
>> Sent: 02 June 2020 10:55
>> To: john@mobius-embedded-systems.co.uk
>> <andrew@mobius-embedded-systems.co.uk>; barebox@lists.infradead.org
>> Subject: Re: Mini UART support for Raspberry Pi CM3 ?
>>
>> On 6/2/20 11:43 AM, Ahmad Fatoum wrote:
>>> On 6/2/20 11:14 AM, john@mobius-embedded-systems.co.uk wrote:
>>>> Hi
>>>>
>>>> I have been trying to get the mini UART (UART1) to work in Barebox 
>>>> on the RPI Compute Module 3+.  I already have the changes made in 
>>>> config.txt and this works fine when I boot into the main Linux code.
>>>> However, in Barebox, the output always comes out on the main UART
>>>> (UART0) and that is wired to the Bluetooth module on my platform.  I 
>>>> have
>> tried modifying the device
>>>> trees and cannot seem to get any output.   I also ensured that I added
>> the
>>>> RPI CM3 output target as a config in rpi_defconfig.   
>>>>
>>>> I've tried turning off the PL011 config option and also changing the 
>>>> device tree to reference UART1 and set the chosen stdout-path to 
>>>> point to this UART, but when I do this I just get a lack of any 
>>>> serial
>> output.
>>>>
>>>> I am also wanting to use the alternate pins (32 & 33) for UART1, so 
>>>> I am thinking that something else needs to be changed.  Has anyone 
>>>> managed to get this to work?
>>>
>>> Which barebox version are you on? v2020.03.0 contains a series for 
>>> mini UART support culminating in ab76f9d09d3b ("ARM: rpi: choose 
>>> miniuart as stdout"), which sounds like something you will want to have.
>>
>> Oh, I see now that this is in since v2019.03.0. I assume you are 
>> already on a newer version?
>>
>>> Also what's you "Console activation strategy"? (Kconfig symbols
>>> CONSOLE_ACTIVATE_.*) You'll want to have CONSOLE_ACTIVATE_NONE, so 
>>> only the stdout-path from the device tree is activated by default.
>>>
>>> Cheers
>>> Ahmad
>>>
>>>>
>>>> Regards
>>>>
>>>> John
>>>>
>>>>
>>>> _______________________________________________
>>>> barebox mailing list
>>>> barebox@lists.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/barebox
>>>>
>>>
>>
> 

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