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

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Date:   Thu, 30 Nov 2017 21:36:35 +0000
From:   James Hogan <james.hogan@...s.com>
To:     David Daney <david.daney@...ium.com>
CC:     <linux-mips@...ux-mips.org>, <ralf@...ux-mips.org>,
        <netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>,
        "Rob Herring" <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        <devel@...verdev.osuosl.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>,
        "Steven J. Hill" <steven.hill@...ium.com>,
        <devicetree@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Carlos Munoz <cmunoz@...ium.com>
Subject: Re: [PATCH v4 2/8] MIPS: Octeon: Enable LMTDMA/LMTST operations.

On Tue, Nov 28, 2017 at 04:55:34PM -0800, David Daney wrote:
> From: Carlos Munoz <cmunoz@...ium.com>
> 
> LMTDMA/LMTST operations move data between cores and I/O devices:
> 
> * LMTST operations can send an address and a variable length
>   (up to 128 bytes) of data to an I/O device.
> * LMTDMA operations can send an address and a variable length
>   (up to 128) of data to the I/O device and then return a
>   variable length (up to 128 bytes) response from the IOI device.

Should that be "I/O"?

> 
> Signed-off-by: Carlos Munoz <cmunoz@...ium.com>
> Signed-off-by: Steven J. Hill <Steven.Hill@...ium.com>
> Signed-off-by: David Daney <david.daney@...ium.com>
> ---
>  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?

> +	}
>  	/* R/W If set, CVMSEG is available for loads/stores in
>  	 * supervisor mode. */
>  	cvmmemctl.s.cvmsegenas = 0;
> diff --git a/arch/mips/include/asm/octeon/octeon.h b/arch/mips/include/asm/octeon/octeon.h
> index c99c4b6a79f4..92a17d67c1fa 100644
> --- a/arch/mips/include/asm/octeon/octeon.h
> +++ b/arch/mips/include/asm/octeon/octeon.h
> @@ -179,7 +179,15 @@ union octeon_cvmemctl {
>  		/* RO 1 = BIST fail, 0 = BIST pass */
>  		__BITFIELD_FIELD(uint64_t wbfbist:1,
>  		/* Reserved */
> -		__BITFIELD_FIELD(uint64_t reserved:17,
> +		__BITFIELD_FIELD(uint64_t reserved_52_57:6,
> +		/* When set, LMTDMA/LMTST operations are permitted */
> +		__BITFIELD_FIELD(uint64_t lmtena:1,
> +		/* Selects the CVMSEG LM cacheline used by LMTDMA
> +		 * LMTST and wide atomic store operations.
> +		 */
> +		__BITFIELD_FIELD(uint64_t lmtline:6,
> +		/* Reserved */
> +		__BITFIELD_FIELD(uint64_t reserved_41_44:4,
>  		/* OCTEON II - TLB replacement policy: 0 = bitmask LRU; 1 = NLU.
>  		 * This field selects between the TLB replacement policies:
>  		 * bitmask LRU or NLU. Bitmask LRU maintains a mask of
> @@ -275,7 +283,7 @@ union octeon_cvmemctl {
>  		/* R/W Size of local memory in cache blocks, 54 (6912
>  		 * bytes) is max legal value. */
>  		__BITFIELD_FIELD(uint64_t lmemsz:6,
> -		;)))))))))))))))))))))))))))))))))
> +		;))))))))))))))))))))))))))))))))))))
>  	} s;
>  };

Regardless, the patch looks good to me.

Reviewed-by: James Hogan <jhogan@...nel.org>

Cheers
James

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