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

[Stefan Roese]

Hi Marek,

On 09.11.2015 01:10, Marek Vasut wrote:
> On Thursday, September 17, 2015 at 05:30:29 PM, Stefan Roese wrote:
>
> Hi!
>
>> By not defining CONFIG_SYS_ARM_CACHE_WRITEALLOC, the WRITEBACK cache
>> policy is selected. This leads to much better performance on the SoCFPGA.
>> A quick network test shows this:
>>
>> Without this patch:
>> => tftp 100000 big-40mb
>> Speed: 1000, full duplex
>> Using dwmac.ff702000 device
>> TFTP from server 192.168.1.54; our IP address is 192.168.1.252
>> Filename 'big-40mb'.
>> Load address: 0x100000
>> Loading: #################################################################
>>           #################################################################
>>           #################################################################
>>           #################################################################
>>           ##########################
>>           2.5 MiB/s
>>
>> With this patch:
>> => tftp 100000 big-40mb
>> Speed: 1000, full duplex
>> Using dwmac.ff702000 device
>> TFTP from server 192.168.1.54; our IP address is 192.168.1.252
>> Filename 'big-40mb'.
>> Load address: 0x100000
>> Loading: #################################################################
>>           #################################################################
>>           #################################################################
>>           #################################################################
>>           ##########################
>>           7.6 MiB/s
>>
>> A performance improvement of factor ~3.
>>
>> Signed-off-by: Stefan Roese <sr at denx.de>
>> Cc: Dinh Nguyen <dinguyen at opensource.altera.com>
>> Cc: Chin Liang See <clsee at altera.com>
>> Cc: Pavel Machek <pavel at denx.de>
>> Cc: Marek Vasut <marex at denx.de>
>> ---
>>   include/configs/socfpga_common.h | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/include/configs/socfpga_common.h
>> b/include/configs/socfpga_common.h index 38ae763..a2811ba 100644
>> --- 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.

HTP.

Thanks,
Stefan