Re: [PATCH] PPC440EPx SDRAM width

[Valentine Barshak <vbarshak@ru.mvista.com>]

Josh Boyer wrote:
> On Thu, Apr 23, 2009 at 06:40:48PM +0400, Valentine Barshak wrote:
>> Stefan Roese wrote:
>>> On Thursday 23 April 2009, Josh Boyer wrote:
>>>> On Thu, Apr 23, 2009 at 09:36:12AM -0400, Steven A. Falco wrote:
>>>>> There is an error in the way ibm4xx_denali_fixup_memsize calculates
>>>>> memory size.  When testing the DDR_REDUC bit, the polarity is
>>>>> backwards.  A "1" implies 32-bit wide memory while a "0" implies
>>>>> 64-bit wide memory.
>>>>>
>>>>> For a 32-bit wide system, this bug causes twice the memory to be
>>>>> reported, leading to boot failure.
>>>>>
>>>>> Signed-off-by: Steven A. Falco <sfalco@harris.com>
>>>> So we had a previous patch for this, and a very long discussion on what the
>>>> right solution was.  Either we never came to a resolution, or I have just
>>>> forgotten what it was.
>>>>
>>>> Stefan, Valentine, do either of you remember?
>> The patch will break sequia/rainier since u-boot doesn't set the number  
>> of chipselects correctly for them. IIRC, the last conversation didn't  
>> come to any conclusion. We sort of wanted to fix that regardless of  
>> whether we had corrected u-boot or not.
>>
>> Could we use a "model" property to distinguish between the "real"  
>> sequoia/rainier and other custom boards?
>> If yes, we could add a workaround the ibm4xx_denali_fixup_memsize to  
>> hardcode the chipselect number to 1 for sequoia/rainier.
> 
> We could do that perhaps, yes.  In cases where the board has a newer U-Boot
> with the fix already, it shouldn't really cause any harm, correct?

Yes, that's correct.

Thanks,
Val

> 
> josh