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From: Will Deacon <will.deacon@arm.com>
To: Laura Abbott <labbott@redhat.com>
Cc: "Sumit Semwal" <sumit.semwal@linaro.org>,
	"John Stultz" <john.stultz@linaro.org>,
	"Arve Hjønnevåg" <arve@android.com>,
	"Riley Andrews" <riandrews@android.com>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	linaro-mm-sig@lists.linaro.org, devel@driverdev.osuosl.org,
	"Russell King" <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Eun Taik Lee" <eun.taik.lee@samsung.com>,
	"Rohit kumar" <rohit.kr@samsung.com>,
	"Liviu Dudau" <Liviu.Dudau@arm.com>,
	"Jon Medhurst" <tixy@linaro.org>,
	"Jeremy Gebben" <jgebben@codeaurora.org>,
	"Bryan Huntsman" <bryanh@codeaurora.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Android Kernel Team" <kernel-team@android.com>,
	"Arnd Bergmann" <arnd@arndb.de>
Subject: Re: [RFCv3][PATCH 3/5] arm64: Implement ARCH_HAS_FORCE_CACHE
Date: Tue, 13 Sep 2016 16:14:03 +0100	[thread overview]
Message-ID: <20160913151325.GF17731@arm.com> (raw)
In-Reply-To: <27805ccf-1f2d-81ea-044e-b21207be8e7f@redhat.com>

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 <labbott@redhat.com>
> >>---
> >>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

WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFCv3][PATCH 3/5] arm64: Implement ARCH_HAS_FORCE_CACHE
Date: Tue, 13 Sep 2016 16:14:03 +0100	[thread overview]
Message-ID: <20160913151325.GF17731@arm.com> (raw)
In-Reply-To: <27805ccf-1f2d-81ea-044e-b21207be8e7f@redhat.com>

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 <labbott@redhat.com>
> >>---
> >>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

  reply	other threads:[~2016-09-13 15:14 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-12 21:32 [RFCv3][PATCH 0/5] Cleanup Ion mapping/caching Laura Abbott
2016-09-12 21:32 ` Laura Abbott
2016-09-12 21:32 ` [RFCv3][PATCH 1/5] Documentation: Introduce kernel_force_cache_* APIs Laura Abbott
2016-09-12 21:32   ` Laura Abbott
2016-09-12 21:32 ` [RFCv3][PATCH 2/5] arm: Impelment ARCH_HAS_FORCE_CACHE Laura Abbott
2016-09-12 21:32   ` Laura Abbott
2016-09-12 21:32 ` [RFCv3][PATCH 3/5] arm64: Implement ARCH_HAS_FORCE_CACHE Laura Abbott
2016-09-12 21:32   ` Laura Abbott
2016-09-13  9:19   ` Will Deacon
2016-09-13  9:19     ` Will Deacon
2016-09-13 15:02     ` Laura Abbott
2016-09-13 15:02       ` Laura Abbott
2016-09-13 15:14       ` Will Deacon [this message]
2016-09-13 15:14         ` Will Deacon
2016-09-13 18:41         ` Laura Abbott
2016-09-13 18:41           ` Laura Abbott
2017-02-21  6:05           ` [Linaro-mm-sig] " Chen Feng
2017-02-21  6:05             ` Chen Feng
2017-02-21 19:29             ` Laura Abbott
2017-02-21 19:29               ` Laura Abbott
2017-02-23  1:01               ` Chen Feng
2017-02-23  1:01                 ` Chen Feng
2017-02-23 16:03                 ` Laura Abbott
2017-02-23 16:03                   ` Laura Abbott
2016-09-12 21:32 ` [RFCv3][PATCH 4/5] staging: android: ion: Convert to the kernel_force_cache APIs Laura Abbott
2016-09-12 21:32   ` Laura Abbott
2016-09-12 21:32 ` [RFCv3][PATCH 5/5] staging: ion: Add support for syncing with DMA_BUF_IOCTL_SYNC Laura Abbott
2016-09-12 21:32   ` Laura Abbott

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