From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-iy0-f179.google.com (mail-iy0-f179.google.com [209.85.210.179]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id DF2D5B71C8 for ; Fri, 20 May 2011 11:32:20 +1000 (EST) Received: by iym7 with SMTP id 7so2995952iym.38 for ; Thu, 19 May 2011 18:32:17 -0700 (PDT) Message-ID: <4DD5C49E.4050103@gmail.com> Date: Thu, 19 May 2011 20:32:14 -0500 From: Kazutomo Yoshii MIME-Version: 1.0 To: Benjamin Herrenschmidt Subject: Re: [bg-linux] [PATCH 5/7] [RFC] force 32-byte aligned kmallocs References: <1305753895-24845-1-git-send-email-ericvh@gmail.com> <1305753895-24845-5-git-send-email-ericvh@gmail.com> <1305851769.7481.90.camel@pasglop> In-Reply-To: <1305851769.7481.90.camel@pasglop> Content-Type: multipart/alternative; boundary="------------030006080506050206070601" Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, bg-linux@lists.anl-external.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This is a multi-part message in MIME format. --------------030006080506050206070601 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 05/19/2011 07:36 PM, Benjamin Herrenschmidt wrote: > On Wed, 2011-05-18 at 16:24 -0500, Eric Van Hensbergen wrote: > >> For BGP, it is convenient for 'kmalloc' to come back with 32-byte >> aligned units for torus DMA >> >> Signed-off-by: Eric Van Hensbergen >> --- >> arch/powerpc/include/asm/page_32.h | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h >> index 68d73b2..fb0a7ae 100644 >> --- a/arch/powerpc/include/asm/page_32.h >> +++ b/arch/powerpc/include/asm/page_32.h >> @@ -9,7 +9,7 @@ >> >> #define VM_DATA_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS32 >> >> -#ifdef CONFIG_NOT_COHERENT_CACHE >> +#if defined(CONFIG_NOT_COHERENT_CACHE) || defined(CONFIG_BGP) >> #define ARCH_DMA_MINALIGN L1_CACHE_BYTES >> #endif >> > Is DMA cache coherent on BG/P ? That's odd for a 4xx base :-) > Actually DMA sends invalidate requests to the snoop unit(L2 level). BGP SoC is a bit different from other 4xx base. Some details can be found in www.scc.acad.bg/documentation/team.pdf - kaz > Cheers, > Ben. > > > > _______________________________________________ > bg-linux mailing list > bg-linux@lists.anl-external.org > https://lists.anl-external.org/mailman/listinfo/bg-linux > http://bg-linux.anl-external.org/wiki > --------------030006080506050206070601 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit On 05/19/2011 07:36 PM, Benjamin Herrenschmidt wrote: 
On Wed, 2011-05-18 at 16:24 -0500, Eric Van Hensbergen wrote:
  
For BGP, it is convenient for 'kmalloc' to come back with 32-byte
aligned units for torus DMA

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
---
 arch/powerpc/include/asm/page_32.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/page_32.h b/arch/powerpc/include/asm/page_32.h
index 68d73b2..fb0a7ae 100644
--- a/arch/powerpc/include/asm/page_32.h
+++ b/arch/powerpc/include/asm/page_32.h
@@ -9,7 +9,7 @@
 
 #define VM_DATA_DEFAULT_FLAGS	VM_DATA_DEFAULT_FLAGS32
 
-#ifdef CONFIG_NOT_COHERENT_CACHE
+#if defined(CONFIG_NOT_COHERENT_CACHE) || defined(CONFIG_BGP)
 #define ARCH_DMA_MINALIGN	L1_CACHE_BYTES
 #endif
    
Is DMA cache coherent on BG/P ? That's odd for a 4xx base :-)

Actually DMA sends invalidate requests to the snoop unit(L2 level).
BGP SoC is a bit different from other 4xx base.

Some details can be found in
www.scc.acad.bg/documentation/team.pdf

- kaz

Cheers,
Ben.



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