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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-06-27 at 16:59 +0800, Chen Baozi wrote:
> On Jun 27, 2013, at 4:54 PM, Chen Baozi <baozich@xxxxxxxxx> wrote:
> 
> > 
> > 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?
> Sorry, 8250.

Phew, I was wondering what a 9250 was ;-)

> 
> > 
> >> 
> >> 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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