[U-Boot] [PATCH 2/2] arm: socfpga: enable data/inst prefetch and shared override in the L2

[Marek Vasut]

On Wednesday, October 14, 2015 at 06:32:42 PM, Pavel Machek wrote:
> On Mon 2015-10-12 09:59:57, dinguyen at opensource.altera.com wrote:
> > From: Dinh Nguyen <dinguyen at opensource.altera.com>
> > 
> > Update the L2 AUX CTRL settings for the SoCFPGA.
> > 
> > Enabling D and I prefetch bits helps improve SDRAM performance on the
> > platform.
> > 
> > Also, we need to enable bit 22 of the L2. By not having bit 22 set in the
> > PL310 Auxiliary Control register (shared attribute override enable) has
> > the side effect of transforming Normal Shared Non-cacheable reads into
> > Cacheable no-allocate reads.
> > 
> > Coherent DMA buffers in Linux always have a Cacheable alias via the
> > kernel linear mapping and the processor can speculatively load cache
> > lines into the PL310 controller. With bit 22 cleared, Non-cacheable
> > reads would unexpectedly hit such cache lines leading to buffer
> > corruption.
> > 
> > Signed-off-by: Dinh Nguyen <dinguyen at opensource.altera.com>
> > ---
> > 
> >  arch/arm/include/asm/pl310.h |  2 ++
> >  arch/arm/mach-socfpga/misc.c | 12 ++++++++++++
> >  2 files changed, 14 insertions(+)
> > 
> > diff --git a/arch/arm/include/asm/pl310.h b/arch/arm/include/asm/pl310.h
> > index 18b90b7..7a11405 100644
> > --- a/arch/arm/include/asm/pl310.h
> > +++ b/arch/arm/include/asm/pl310.h
> > @@ -17,6 +17,8 @@
> > 
> >  #define L2X0_CTRL_EN				1
> >  
> >  #define PL310_SHARED_ATT_OVERRIDE_ENABLE		(1 << 22)
> > 
> > +#define PL310_AUX_CTRL_DATA_PREFETCH_MASK	(1 << 28)
> > +#define PL310_AUX_CTRL_INST_PREFETCH_MASK	(1 << 29)
> 
> These would be
> 
> arch/arm/include/asm/hardware/cache-l2x0.h:#define
> L310_PREFETCH_CTRL_DATA_PREFETCH     BIT(28)
> arch/arm/include/asm/hardware/cache-l2x0.h:#define
> L310_PREFETCH_CTRL_INSTR_PREFETCH    BIT(29)
> 
> ...in kernel. So maybe staying with L310_ prefix makes sense?
> Otherwise it looks ok.

Why is it L... in one and PL... in the other one ? What does the "PL"
prefix stand for anyway ?

Best regards,
Marek Vasut