progress on the adi pronghorn metro board

[Sam Leffler]

John Hay wrote:
> On Thu, Mar 22, 2007 at 04:27:08PM +0100, Olivier Houchard wrote:
>> On Thu, Mar 22, 2007 at 08:04:21AM -0700, Sam Leffler wrote:
>>> John Hay wrote:
>>>> Hi Guys,
>>>>
>>>> With this patch I am at the stage where both an Avila 2348-4 and the
>>>> ADI Pronghorn Metro boot from the same kernel binary. The "main" stuff
>>>> is working, ie. console, ethernet and mini-pci slots. The iic bus on
>>>> the Avila is still working. The one for the Pronghorn is configured,
>>>> but I must still write a driver for their max6652 temperature/voltage
>>>> sensor before I will know if it is really working.
>>>>
>>>> The biggest difference between the 2 boards are in the 16 GPIO pins.
>>>> I think there is only 1 pin that have the same function. :-/
>>>>
>>>> So what I did was to create a structure and then have 2 instances of
>>>> it, one with Avila values in it and one with Pronghorn values. Then
>>>> early in the boot phase, the board type gets detected and a pointer
>>>> gets set to the relevant structure. All the drivers then use this
>>>> pointer to get the correct values. The efect is that most of the
>>>> drivers needs no checks for the different boards.
>>>>
>>>> What I would like to know is, if this approach is acceptable? Should
>>>> I use different files to put the stuff in?
>>>>
>>>> My code is not finished yet, but I thought that I would like to get
>>>> some feedback. I still have to replace some of the numbers in the
>>>> structure with defined values. I would also like to try and really
>>>> probe the iic devices and not just assume that they are there.
>>> I'm not sure whether it makes sense to support different boards in a
>>> single binary (variations on a board design yes).  My experience is that
>>> embedded applications are often cycle starved and giving up cycles for
>>> flexibility like this is ok only for devel/bringup.  I suspect
>>> compile-time configuration is preferable.
>>>
>>> However if this flexibility is desirable it might be better to use
>>> ivar's hung off the nexus.
>>>
>>> 	Sam
>> I tend to agree. 
>> I think one config file per board is not too much to handle, and detecting
>> which board we're currently running can be difficult.
>>
>> Olivier
> 
> I think my code changes are mostly in the attach routines or routines that
> are used by them, so I don't think it will have an influence on run-time
> speed. The biggest win for me would be that one could build a single
> distro that would be able to run any of the two boards. They are so
> similar, same cpu, 2 ethernets, 4 mini-pcis. But I guess in reality few
> groups/companies will source more than one board for a product.

I thought I saw you change some #define's to variable refs in code the
fiddled with the gpio pins for things like pci interrupt handling.  If
no changes affect the fast paths then I'm fine with adding a board
descriptor and using it instead of hardwired values--but I still think
you might be able to do this more cleanly by hanging the data off the
nexus instead of adding a global variable.

	Sam