Re: [Xen-devel] [PATCH] xen/arm: add OMAP5432 UART support for early_printk

[Chen Baozi <baozich@xxxxxxxxx>]

On Jun 27, 2013, at 4:22 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

> On Thu, 2013-06-27 at 15:20 +0800, Chen Baozi wrote:
>> To enable it, add "CONFIG_EARLY_PRINTK := omap5432" to Config.mk
> 
> From the register offsets this looks like it might be a somewhat 8250
> compatible UART logic block?
From TI's data manual, it is said this is a 16C750 compatible UART. So could it 
be called an 9250 compatible UART?

> 
> Bamvor also implemented a driver for an 8250 like device on the
> sun6i[0]. Rather than having multiple drivers for similar platforms I
> asked him to produce a single configurable 8250 driver. Perhaps you
> could work together to make sure this works for you both?
Sure, it is OK for me.

> 
> Thanks,
> Ian.
> 
> [0] see "xen/arm: introduce Allwinner sun6i SOC basic support"
> <1370004814-30686-3-git-send-email-bjzhang@xxxxxxxx>.
> 
>> +ifeq ($(CONFIG_EARLY_PRINTK), omap5432)
>> +EARLY_PRINTK_INC := omap
>> +EARLY_PRINTK_INIT_UART := y
> 
> Does your bootloader not setup the UART? Preferably we would simply
> inherit that setup (avoids more code and mismatched baud rate etc).
Yes, it does. I thought re-initilization is necessary and found that is also ok 
to inherit the u-boot setup just after finishing the patch. Well, in this case, 
things are much easier :-)

Thanks,

Baozi

> 
> Ian.
> 


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