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

Marek Vasut
2015-11-09T16:02:12Z

On Monday, November 09, 2015 at 04:46:54 PM, Stefan Roese wrote:
> Hi Marek,

Hi!

> 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
>
> ?

Yes I did, but reverting this patch had no impact.

> 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?

I guess we should pester Dinh now :-)