Re: [RESEND PATCH 2/2] arm: socfpga: Set share override bit of the l2 cache controller

[Pavel Machek]

On Thu 2015-02-19 12:13:13, Rob Herring wrote:
> On Thu, Feb 19, 2015 at 11:06 AM,  <dinguyen@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > From: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
> >
> > 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.
> 
> You really should be doing this in your bootloader.
>

You mean... in all your bootloaders? Because there's more
than one.

And as both bootloaders need it, it makes sense to do it 
in kernel, afaict.
							Pavel
> >  DT_MACHINE_START(SOCFPGA, "Altera SOCFPGA")
> >         .l2c_aux_val    = L310_AUX_CTRL_DATA_PREFETCH |
> > -                         L310_AUX_CTRL_INSTR_PREFETCH,
> > +                         L310_AUX_CTRL_INSTR_PREFETCH |
> > +                         L2C_AUX_CTRL_SHARED_OVERRIDE,
> >         .l2c_aux_mask   = ~0,
> >         .smp            = smp_ops(socfpga_smp_ops),
> >         .map_io         = socfpga_map_io,
> > --
> > 2.2.1
> >
> >
> > _______________________________________________
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> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 
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