[U-Boot] [PATCH 1/1] rpi: set serial port clock to 48 MHz

[Mirza Krak]

2016-11-30 19:07 GMT+01:00 Stephen Warren <swarren at wwwdotorg.org>:
> On 11/29/2016 11:47 PM, Mirza Krak wrote:
>>
>> 2016-11-30 5:05 GMT+01:00 Stephen Warren <swarren at wwwdotorg.org>:
>>>
>>> On 11/27/2016 11:05 PM, Mirza Krak wrote:
>>>>
>>>>
>>>> From: Mirza Krak <mirza.krak at gmail.com>
>>>>
>>>> Recently the default UART clock rate has been changed to 48 MHz on all
>>>> pi`s in the firmware files, which broke UART support in u-boot.
>>>>
>>>> Align configuration to boot firmware.
>>>
>>>
>>>
>>>> diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
>>>
>>>
>>>
>>>> @@ -37,7 +37,7 @@ static const struct pl01x_serial_platdata
>>>> serial_platdata = {
>>>>         .base = 0x20201000,
>>>>  #endif
>>>>         .type = TYPE_PL011,
>>>> -       .clock = 3000000,
>>>> +       .clock = 48000000,
>
>
> Now that I look into this some more, I will point out that this code doesn't
> even exist in the latest U-Boot, so your patch doesn't apply.

Yes, my bad. I am on 2016.03. Looking in upstream code I can see that
some changes have been made regarding this.

>
> Instead, the UART is now instantiated from DT:-( Presumably the UART drivers
> attempt to dynamically query the clock rate from the clock provider
> described in DT, yet since there is no such provider implemented in U-Boot,
> this must currently fail, and I presume that if U-Boot still works at all on
> the Pi, then the UART drivers must simply skip programming the divider at
> all, and thus rely on the FW having initialized it.

>From what I see it no longer tries to initialize the UART on RPi at
all and does rely on the FW having initialized it, which seems to be
intentional. See [1].

>
> Does updating to the latest U-Boot code solve your problem?

Will give it a go, but probably solves my problems.

[1]. http://git.denx.de/?p=u-boot.git;a=commit;h=cd0fa5bff8052b19bde6967c2734f323c9848568

Best Regards
Mirza