On Thu 2015-02-19 12:13:13, Rob Herring wrote:
> On Thu, Feb 19, 2015 at 11:06 AM, <dingu...@opensource.altera.com> wrote:
> > From: Dinh Nguyen <dingu...@opensource.altera.com>
> >
> > 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
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-ker...@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
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