Re: [PATCH v3 -next 11/11] serial: 8250_early: Remove setup_early_serial8250_console()

Peter Hurley
2015-04-03T17:38:37Z

On 04/03/2015 12:57 PM, Yinghai Lu wrote:
> On Fri, Apr 3, 2015 at 3:37 AM, Peter Hurley <peter@hurleysoftware.com> wrote:
>> On 04/02/2015 10:38 PM, Yinghai Lu wrote:
>>> On Thu, Apr 2, 2015 at 5:22 PM, Yinghai Lu <yinghai@kernel.org> wrote:
>>>
>>>>>>> still have another problem.
>>>>>>> when using console=uart8250,io,0x3f8
>>>>>>> it works as earlycon at first.
>>>>>>> but after handover to normal console
>>>>>>> it will revert back to 9600 again.
>>>>>>
>>>>>> this regression should be caused by:
>>>>>>
>>>>>> commit c7cef0a84912cab3c9df8949b034e4aa62982ec9
>>>>>> Author: Peter Hurley <peter@hurleysoftware.com>
>>>>>> Date: Mon Mar 9 16:27:12 2015 -0400
>>>>>>
>>>>>> console: Add extensible console matching
>>>>>
>>>> So your whole patchset will need the first patch ?
>>>>
>>>> or can you just drop the first one patch ?
>>>
>>> Please check attached patch that fix regresion by. commit c7cef0a849
>>> ("console: Add extensible console matching")
>>>
>>> or you have better way?
>>
>> Please re-read my first response to this problem.
>>
>
>> Also, this expectation is an impediment when adding support for other
>> 8250-like designs that don't have the same 8250 divisor registers
>> (ie., _every_ new design). To properly support this requirement for
>> just the existing 8250 hardware will require special probe_baud()
>> functions for: dw_8250, intel byt, intel mid, omap_8250, exar 17v35 series,
>> omap 1510.
>
> But you can not break old setup!
>
> old behavior: console=uart8250,io,0x3f8
>
> when bootloader or firmware has 115200 used already,
> earlycon, and console all keep 115200.
>
> Now with your change, earlycon will use 115200 still,
> but console will switch to 9600.
>
>>
>> Is specifying the line speed on the command line really a burden?
>>
>
> Yes. We have two setups, and two BIOS versions.
> product version is using 9600 and devel/debug is using 115200.

Wait -- you have earlycon in a product??

> This is a regression, and must be addressed.
>
> Greg,
>
> Please don't send merge request for tty-next to Linus before
> this regression get resolved.