[U-Boot] [PATCH] mx53: use CONFIG_SYS_L2CACHE_OFF in config file

[Jason Hui]

Hi, Stefano,

On Tue, Jul 26, 2011 at 5:21 PM, Stefano Babic <sbabic at denx.de> wrote:
> On 07/26/2011 10:25 AM, Jason Liu wrote:
>> CONFIG_L2_OFF is obsolete after the following commit:
>>
>> e47f2db5371047eb9bcd115fee084e6a8a92a239
>> armv7: rename cache related CONFIG flags
>> Replace the cache related CONFIG flags with more meaningful
>> names. Following are the changes:
>> CONFIG_L2_OFF      -> CONFIG_SYS_L2CACHE_OFF
>>
>> But the above commit does not clean up all the mx53 board config file.
>> This patch does it by using CONFIG_SYS_L2CACHE_OFF instead of _L2_OFF
>>
>
> Hi Jason,
>
> I agree  that CONFIG_L2_OFF is obsolete and must be removed. However, I
> do not see any application of CONFIG_SYS_L2CACHE_OFF.
>
> If I grep into u-boot code, this config is not used at all for i.MX.
> Indeed, I can find application for OMAP boards:
>
> arch/arm/cpu/armv7/omap3/board.c:#ifndef CONFIG_SYS_L2CACHE_OFF
> arch/arm/cpu/armv7/omap3/board.c:#ifndef CONFIG_SYS_L2CACHE_OFF
> arch/arm/cpu/armv7/s5pc1xx/cache.S:#ifndef CONFIG_SYS_L2CACHE_OFF
> arch/arm/cpu/armv7/omap4/board.c:#ifndef CONFIG_SYS_L2CACHE_OFF
>
> So this setup is usefulness, I think.

It's used before, if you checkout tag: v2011.06

#ifndef CONFIG_L2_OFF
        /* turn off L2 cache */
        l2_cache_disable();
        /* invalidate L2 cache also */
        invalidate_dcache(get_device_type());
#endif
        i = 0;
        /* mem barrier to sync up things */
        asm("mcr p15, 0, %0, c7, c10, 4": :"r"(i));

#ifndef CONFIG_L2_OFF
        l2_cache_enable();
#endif


I still think we need explicitly disable L2 cache first. If it only
omap related, I don't think we need
CONFIG_SYS_L2CACHE_OFF for the global u-boot. If you grep the
CONFIG_SYS_L2CACHE_OFF
under include/configs, you will see a lot of define other than omap platform.

>
> By the way (and I know it is not the same topic), do you mean maybe
> CONFIG_SYS_DCACHE_OFF ? Have you read the thread related to cache
> problems on MX51 ? Maybe we have to disable D_CACHE until we find a fix
> for the drivers. What do you mean ?

Yes, the fec is not working after commit:
c2dd0d45540397704de9b13287417d21049d34c6
armv7: integrate cache maintenance support

It's due to it enable dcache by default if not define
CONFIG_SYS_DCACHE_OFF explicitly.
mxc_fec driver need be fixed or re-write to consider cache safe. I
agree to disable d-cache first.

Jason

>
> Best regards,
> Stefano Babic
>
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