[U-Boot] [PATCH] ppc: Unlock cache-as-ram in a consistent manner

[Kumar Gala]

On Jul 24, 2009, at 8:46 AM, Wolfgang Denk wrote:

> Dear Peter,
>
> In message <20090723190101.C8F8A832E416 at gemini.denx.de> I wrote:
>>
>> In message <1247269570-11406-1-git-send-email-ptyser at xes-inc.com>  
>> you wrote:
>>> Previously, non-e500 architectures only unlocked their data cache  
>>> which
>>> was used as early RAM when booting to Linux using the "bootm"  
>>> command.
>>> This change causes all PPC boards with CONFIG_SYS_INIT_RAM_LOCK  
>>> defined
>>> to unlock their data cache during U-Boot's initialization.  This
>>> improves U-Boot performance and provides a common cache state when
>>> booting to different OSes.
> ...
>> Hm... tested on TQM834x - it's still booting, but flash recognition
>> stopped working:
>
> I git-bisected the problem on TQM834x:
>
> 982adfc610669482a32127282fe489857a92cfe3 is first bad commit
> commit 982adfc610669482a32127282fe489857a92cfe3
> Author: Peter Tyser <ptyser at xes-inc.com>
> Date:   Fri Jul 10 18:46:10 2009 -0500
>
>    ppc: Unlock cache-as-ram in a consistent manner
>
>    Previously, non-e500 architectures only unlocked their data cache  
> which
>    was used as early RAM when booting to Linux using the "bootm"  
> command.
>    This change causes all PPC boards with CONFIG_SYS_INIT_RAM_LOCK  
> defined
>    to unlock their data cache during U-Boot's initialization.  This
>    improves U-Boot performance and provides a common cache state when
>    booting to different OSes.
>
>    Signed-off-by: Peter Tyser <ptyser at xes-inc.com>
>
> :040000 040000 bf1093b8403580234125df8e97d948c318e8965f  
> 5dce3a5e28ea46706aba44ec62e88584883d0cc4 M   lib_ppc
>
>
> Please suggest how to continue. Shall I revert this commit?

Revert it for now.  I think the problem is that the  
unlock_ram_in_cache is technically buggy on 83xx/74xx_7xx/86xx  
platforms.  We end up flash invalidating the d-cache I think we lose  
data by doing that.  This just happens to work when we call it via  
bootm.

- k