[PATCH] PPC440EPx SDRAM width
jwboyer at linux.vnet.ibm.com
Fri Apr 24 00:59:15 EST 2009
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 at 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?
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