[U-Boot] [PATCH] arm: socfpga: Actually enable L2 cache

[Marek Vasut <marex@denx.de>]

On Sunday, December 20, 2015 at 03:38:54 AM, Stefan Roese wrote:
> On 19.12.2015 17:31, Marek Vasut wrote:
> > On Saturday, December 19, 2015 at 11:03:45 AM, Stefan Roese wrote:
> >> On 19.12.2015 06:58, Marek Vasut wrote:
> >>> The L2 cache was never enabled in the v7_outer_cache_enable(), fix
> >>> this and enable the L2 cache.
> >>> 
> >>> Signed-off-by: Marek Vasut <marex@denx.de>
> >>> Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
> >>> Cc: Chin Liang See <clsee@altera.com>
> >>> ---
> >>> 
> >>>    arch/arm/mach-socfpga/misc.c | 7 +++++--
> >>>    1 file changed, 5 insertions(+), 2 deletions(-)
> >>> 
> >>> diff --git a/arch/arm/mach-socfpga/misc.c
> >>> b/arch/arm/mach-socfpga/misc.c index b110f5b..621f5d9 100644
> >>> --- a/arch/arm/mach-socfpga/misc.c
> >>> +++ b/arch/arm/mach-socfpga/misc.c
> >>> @@ -54,14 +54,17 @@ void enable_caches(void)
> >>> 
> >>>    void v7_outer_cache_enable(void)
> >>>    {
> >>> 
> >>> -	/* disable the L2 cache */
> >>> -	writel(0, &pl310->pl310_ctrl);
> >>> +	/* Disable the L2 cache */
> >>> +	clrbits_le32(&pl310->pl310_ctrl, L2X0_CTRL_EN);
> >>> 
> >>>    	/* enable BRESP, instruction and data prefetch, full line of 
zeroes
> >>>    	*/ setbits_le32(&pl310->pl310_aux_ctrl,
> >>>    	
> >>>    		     L310_AUX_CTRL_DATA_PREFETCH_MASK |
> >>>    		     L310_AUX_CTRL_INST_PREFETCH_MASK |
> >>>    		     L310_SHARED_ATT_OVERRIDE_ENABLE);
> >>> 
> >>> +
> >>> +	/* Enable the L2 cache */
> >>> +	setbits_le32(&pl310->pl310_ctrl, L2X0_CTRL_EN);
> >> 
> >> Thanks Marek. I would be interested in some number here. Do you see
> >> a bigger change in the performance (ethernet driver or dhrystone)
> >> by enabling the L2 cache?
> > 
> > Neither, but I didn't see any improvement on MX6 when I enabled L2
> > either.
> 
> Then my feeling is, that some other configuration is needed to
> effectively enable the L2 cache on those platforms. Sorry, but
> I have no clear suggestions right now. Other than to look at
> Linux for the L2 cache enabling.

The L2 cache is enabled, but the slowdown is not induced by the L2 cache.
The L2 cache has no performance impact on other platforms either. Did you
observe actual performance improvement with L2 cache ON anywhere ?

Best regards,
Marek Vasut