[U-Boot] [PATCH] arm: socfpga: Fix cache configuration

[Stefan Roese]

Hi Marek,

On 09.11.2015 14:49, Marek Vasut wrote:

<snip>

>>>> --- a/include/configs/socfpga_common.h
>>>> +++ b/include/configs/socfpga_common.h
>>>> @@ -73,7 +73,6 @@
>>>>
>>>>    /*
>>>>    
>>>>     * Cache
>>>>     */
>>>>
>>>> -#define CONFIG_SYS_ARM_CACHE_WRITEALLOC
>>>>
>>>>    #define CONFIG_SYS_CACHELINE_SIZE 32
>>>>    #define CONFIG_SYS_L2_PL310
>>>>    #define CONFIG_SYS_PL310_BASE		SOCFPGA_MPUL2_ADDRESS
>>>
>>> I hate to say it, but I am running into issues with this patch :-(
>>
>> I'm sorry to hear this.
>>
>>> I use a standard USB stick here and with this patch, I am getting the
>>> following failure (with enabled and disabled cache):
>>>
>>> => usb reset
>>> resetting USB...
>>> USB0:   Core Release: 2.93a
>>> scanning bus 0 for devices... unable to get descriptor, error 0
>>> usb_new_device: Cannot read configuration, skipping device 058f:6387
>>> 1 USB Device(s) found
>>>
>>>          scanning usb for storage devices... 0 Storage Device(s) found
>>>
>>> => dcache off
>>> => usb reset
>>> resetting USB...
>>> USB0:   Core Release: 2.93a
>>> scanning bus 0 for devices... 2 USB Device(s) found
>>>
>>>          scanning usb for storage devices... 1 Storage Device(s) found
>>>
>>> If I revert this patch, my USB stick works as well.
>>>
>>> I am also aware that Stefan mentions that without this patch, cache is
>>> not enabled at all. On the other hand, I cannot find any obviously
>>> faulty behavior in the dwc2 driver, it does
>>> flush_dcache_range()/invalidate_dcache_range() in the right places.
>>>
>>> Any ideas please ?
>>
>> Perhaps its a timing related issue? As the code is executed faster
>> with cache enabled. Just an idea - perhaps there is still some ugly
>> code that doesn't do proper timer based loops / delays.
> 
> I doubt that's not the case. If I disable cache just around the hcdma bit
> in the driver (disable before the flush_dcache_range() and enable after
> invalidate_dcache_range() in the driver), it still fails.

Did you check if this problem is perhaps also related to Dinh's L2
cache patch:

8d8e13e1 arm: socfpga: enable data/inst prefetch and shared override in the L2

?

I just noticed, that here the L2 cache gets disabled and is not
enabled again in function v7_outer_cache_enable(). This looks a
bit suspicious.

Dinh, did you perhaps miss to re-enable the L2 cache after the
aux_ctrl register setup again?

Thanks,
Stefan