From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758835AbcIMPON (ORCPT ); Tue, 13 Sep 2016 11:14:13 -0400 Received: from foss.arm.com ([217.140.101.70]:51336 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751488AbcIMPOJ (ORCPT ); Tue, 13 Sep 2016 11:14:09 -0400 Date: Tue, 13 Sep 2016 16:14:03 +0100 From: Will Deacon To: Laura Abbott Cc: Sumit Semwal , John Stultz , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Riley Andrews , Daniel Vetter , linaro-mm-sig@lists.linaro.org, devel@driverdev.osuosl.org, Russell King , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Eun Taik Lee , Rohit kumar , Liviu Dudau , Jon Medhurst , Jeremy Gebben , Bryan Huntsman , Greg Kroah-Hartman , Android Kernel Team , Arnd Bergmann Subject: Re: [RFCv3][PATCH 3/5] arm64: Implement ARCH_HAS_FORCE_CACHE Message-ID: <20160913151325.GF17731@arm.com> References: <1473715978-11633-1-git-send-email-labbott@redhat.com> <1473715978-11633-4-git-send-email-labbott@redhat.com> <20160913091946.GB7467@arm.com> <27805ccf-1f2d-81ea-044e-b21207be8e7f@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27805ccf-1f2d-81ea-044e-b21207be8e7f@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 13, 2016 at 08:02:20AM -0700, Laura Abbott wrote: > On 09/13/2016 02:19 AM, Will Deacon wrote: > >On Mon, Sep 12, 2016 at 02:32:56PM -0700, Laura Abbott wrote: > >> > >>arm64 may need to guarantee the caches are synced. Implement versions of > >>the kernel_force_cache API to allow this. > >> > >>Signed-off-by: Laura Abbott > >>--- > >>v3: Switch to calling cache operations directly instead of relying on > >>DMA mapping. > >>--- > >> arch/arm64/include/asm/cacheflush.h | 8 ++++++++ > >> arch/arm64/mm/cache.S | 24 ++++++++++++++++++++---- > >> arch/arm64/mm/flush.c | 11 +++++++++++ > >> 3 files changed, 39 insertions(+), 4 deletions(-) > > > >I'm really hesitant to expose these cache routines as an API solely to > >support a driver sitting in staging/. I appreciate that there's a chicken > >and egg problem here, but we *really* don't want people using these routines > >in preference to the DMA API, and I fear that we'll simply grow a bunch > >more users of these things if we promote it as an API like you're proposing. > > > >Can the code not be contained under staging/, as part of ion? > > > > I proposed that in V1 and it was suggested I make it a proper API > > http://www.mail-archive.com/driverdev-devel@linuxdriverproject.org/msg47654.html > http://www.mail-archive.com/driverdev-devel@linuxdriverproject.org/msg47672.html :/ then I guess we're in disagreement. If ion really needs this stuff (which I don't fully grok), perhaps we should be exposing something at a higher level from the architecture, so it really can't be used for anything other than ion. Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 13 Sep 2016 16:14:03 +0100 Subject: [RFCv3][PATCH 3/5] arm64: Implement ARCH_HAS_FORCE_CACHE In-Reply-To: <27805ccf-1f2d-81ea-044e-b21207be8e7f@redhat.com> References: <1473715978-11633-1-git-send-email-labbott@redhat.com> <1473715978-11633-4-git-send-email-labbott@redhat.com> <20160913091946.GB7467@arm.com> <27805ccf-1f2d-81ea-044e-b21207be8e7f@redhat.com> Message-ID: <20160913151325.GF17731@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Sep 13, 2016 at 08:02:20AM -0700, Laura Abbott wrote: > On 09/13/2016 02:19 AM, Will Deacon wrote: > >On Mon, Sep 12, 2016 at 02:32:56PM -0700, Laura Abbott wrote: > >> > >>arm64 may need to guarantee the caches are synced. Implement versions of > >>the kernel_force_cache API to allow this. > >> > >>Signed-off-by: Laura Abbott > >>--- > >>v3: Switch to calling cache operations directly instead of relying on > >>DMA mapping. > >>--- > >> arch/arm64/include/asm/cacheflush.h | 8 ++++++++ > >> arch/arm64/mm/cache.S | 24 ++++++++++++++++++++---- > >> arch/arm64/mm/flush.c | 11 +++++++++++ > >> 3 files changed, 39 insertions(+), 4 deletions(-) > > > >I'm really hesitant to expose these cache routines as an API solely to > >support a driver sitting in staging/. I appreciate that there's a chicken > >and egg problem here, but we *really* don't want people using these routines > >in preference to the DMA API, and I fear that we'll simply grow a bunch > >more users of these things if we promote it as an API like you're proposing. > > > >Can the code not be contained under staging/, as part of ion? > > > > I proposed that in V1 and it was suggested I make it a proper API > > http://www.mail-archive.com/driverdev-devel at linuxdriverproject.org/msg47654.html > http://www.mail-archive.com/driverdev-devel at linuxdriverproject.org/msg47672.html :/ then I guess we're in disagreement. If ion really needs this stuff (which I don't fully grok), perhaps we should be exposing something at a higher level from the architecture, so it really can't be used for anything other than ion. Will