[U-Boot] 8/16 bit support for NAND at runtime

[Vipin KUMAR <vipin.kumar@st.com>]

On 3/4/2010 5:58 PM, Wolfgang Denk wrote:
> Dear Vipin KUMAR,
> 
> In message <4B8F8C3F.6050703@st.com> you wrote:
>>
>> This query is wrt NAND 8/16 bit device support at runtime. Currently,
>> the u-boot code can support only one of these at a time.
> 
> Yes, indeed. I have yet to see a piece of hardware which implements
> both 8 and 16 bit interfaces on a single board. Hardware designers
> often have funny ideas, but this seems to be too weird even for them
> ;-)
> 
>> Although it matches the buswidth selected through chip->options and the
>> the buswidth of device id it reads and returns an error if they don't 
>> match, probably a better way can be to reinitialize NAND controller 
>> based on 16 bit device and re-read the device id.
> 
> Why would that be needed? Do you really expect to see both types of
> interfaces on the same piece of hardware?
> 

Yes, that's precisely the case with Spear SoC. It has an FSMC controller
embedded in it. FSMC can support 8 as well as 16 bit devices(off-course
with different initializations) for different banks

> 
> Otherwise you just have misconfigured your board, and fixing the
> configuration should all that is needed to make the code work.  Or am
> I missing something?
> 

I could make the code work with both 8 as well as 16 bit devices. The
only thing is that I have to make a few changes and rebuild the uboot
for a particular interface

> Best regards,
> 
> Wolfgang Denk
>