Subject: Re: [PATCH v4 2/8] MIPS: Octeon: Enable LMTDMA/LMTST operations.

From: James Hogan <[email-masked]>
Date: Thu, 30 Nov 2017 22:56:15 +0000

On Thu, Nov 30, 2017 at 01:49:43PM -0800, David Daney wrote:
> On 11/30/2017 01:36 PM, James Hogan wrote:
> > On Tue, Nov 28, 2017 at 04:55:34PM -0800, David Daney wrote:
> >> Signed-off-by: Carlos Munoz <[email-masked]>
> >> Signed-off-by: Steven J. Hill <[email-masked]>
> >> Signed-off-by: David Daney <[email-masked]>
> >> ---
> >>   arch/mips/cavium-octeon/setup.c       |  6 ++++++
> >>   arch/mips/include/asm/octeon/octeon.h | 12 ++++++++++--
> >>   2 files changed, 16 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
> >> index a8034d0dcade..99e6a68bc652 100644
> >> --- a/arch/mips/cavium-octeon/setup.c
> >> +++ b/arch/mips/cavium-octeon/setup.c
> >> @@ -609,6 +609,12 @@ void octeon_user_io_init(void)
> >>   #else
> >>   	cvmmemctl.s.cvmsegenak = 0;
> >>   #endif
> >> +	if (OCTEON_IS_OCTEON3()) {
> >> +		/* Enable LMTDMA */
> >> +		cvmmemctl.s.lmtena = 1;
> >> +		/* Scratch line to use for LMT operation */
> >> +		cvmmemctl.s.lmtline = 2;
> > 
> > Out of curiosity, is there significance to the value 2 and associated
> > virtual address 0xffffffffffff8100, or is it pretty arbitrary?
> 
> Yes, there is significance.
> 
> CPU local memory starts at 0xffffffffffff8000, each line is 0x80 bytes. 
> so the 2nd line starts at 0xffffffffffff8100

What I mean is, why is 2 chosen instead of any other value?

Cheers
James