Re: [PATCH 2/2] dma: mv_xor: Use high_base mmio where appropriate
From: Thomas Petazzoni
Date: Tue Oct 29 2013 - 05:38:21 EST
On Tue, 29 Oct 2013 05:34:08 -0300, Ezequiel Garcia wrote:
> > On Mon, Oct 28, 2013 at 3:54 PM, Ezequiel Garcia
> > <ezequiel.garcia@xxxxxxxxxxxxxxxxxx> wrote:
> > > Despite requesting two memory resources, called 'base' and 'high_base', the
> > > driver uses explicitly only the former. The latter is being used implicitly
> > > by addressing at offset +0x200, which in practice accesses high_base.
> > >
> > > Instead of relying in such trick, let's define the registers with the
> > > offset from high_base, and use high_base explicitly where appropriate.
> > >
> > > Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> > > ---
> > > drivers/dma/mv_xor.c | 3 ++-
> > > drivers/dma/mv_xor.h | 25 +++++++++++++------------
> > > 2 files changed, 15 insertions(+), 13 deletions(-)
> > Since it's unused I'd prefer a patch that just deletes xor_high_base.
> It's wrongly *unused*, the mmio high_base is actually being used
> implicitly by always addressing at an offset that addresses +200.
> Deleting high_base would actually make it worse, for that region
> will no longer be ioremaped. Maybe the commit message is not clear
> about it?
I agree with Ezequiel, and I believe his patch is appropriate. The
registers for the XOR engines are indeed split in two areas, so it
makes sense to have this xor_base / xor_high_base split that reflects
the register mapping passed from the Device Tree, and use this split in
the macros used to access the registers.
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
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