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From: Christoph Hellwig <hch@lst.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Clark <robdclark@chromium.org>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	David Airlie <airlied@linux.ie>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Sean Paul <sean@poorly.run>, Rob Clark <robdclark@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	Daniel Vetter <daniel@ffwll.ch>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>, Christoph Hellwig <hch@lst.de>,
	Allison Randal <allison@lohutok.net>
Subject: Re: [PATCH 1/2] drm: add cache support for arm64
Date: Thu, 8 Aug 2019 09:53:51 +0200	[thread overview]
Message-ID: <20190808075351.GC30308@lst.de> (raw)
In-Reply-To: <20190807123807.GD54191@lakrids.cambridge.arm.com>

On Wed, Aug 07, 2019 at 01:38:08PM +0100, Mark Rutland wrote:
> > I *believe* that there are not alias mappings (that I don't control
> > myself) for pages coming from
> > shmem_file_setup()/shmem_read_mapping_page()..  
> 
> AFAICT, that's regular anonymous memory, so there will be a cacheable
> alias in the linear/direct map.

Yes.  Although shmem is in no way special in that regard.  Even with the
normal dma_alloc_coherent implementation on arm and arm64 we keep the
cacheable alias in the direct mapping and just create a new non-cacheable
one.  The only exception are CMA allocations on 32-bit arm, which do
get remapped to uncachable in place.

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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Clark <robdclark@chromium.org>,
	Christoph Hellwig <hch@lst.de>, Rob Clark <robdclark@gmail.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel@ffwll.ch>,
	Allison Randal <allison@lohutok.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] drm: add cache support for arm64
Date: Thu, 8 Aug 2019 09:53:51 +0200	[thread overview]
Message-ID: <20190808075351.GC30308@lst.de> (raw)
In-Reply-To: <20190807123807.GD54191@lakrids.cambridge.arm.com>

On Wed, Aug 07, 2019 at 01:38:08PM +0100, Mark Rutland wrote:
> > I *believe* that there are not alias mappings (that I don't control
> > myself) for pages coming from
> > shmem_file_setup()/shmem_read_mapping_page()..  
> 
> AFAICT, that's regular anonymous memory, so there will be a cacheable
> alias in the linear/direct map.

Yes.  Although shmem is in no way special in that regard.  Even with the
normal dma_alloc_coherent implementation on arm and arm64 we keep the
cacheable alias in the direct mapping and just create a new non-cacheable
one.  The only exception are CMA allocations on 32-bit arm, which do
get remapped to uncachable in place.

  parent reply	other threads:[~2019-08-08  7:54 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05 21:14 [PATCH 1/2] drm: add cache support for arm64 Rob Clark
2019-08-05 21:14 ` Rob Clark
2019-08-05 21:14 ` [PATCH 2/2] drm/msm: use drm_cache when available Rob Clark
2019-08-05 21:14   ` Rob Clark
2019-08-06  8:48 ` [PATCH 1/2] drm: add cache support for arm64 Christoph Hellwig
2019-08-06  8:48   ` Christoph Hellwig
2019-08-06  9:38   ` Daniel Vetter
2019-08-06  9:38     ` Daniel Vetter
2019-08-06  9:38     ` Daniel Vetter
2019-08-06 11:38     ` Christoph Hellwig
2019-08-06 11:38       ` Christoph Hellwig
2019-08-06 14:11   ` Rob Clark
2019-08-06 14:11     ` Rob Clark
2019-08-06 14:34     ` Mark Rutland
2019-08-06 14:34       ` Mark Rutland
2019-08-06 16:31       ` Rob Clark
2019-08-06 16:31         ` Rob Clark
2019-08-07 12:38         ` Mark Rutland
2019-08-07 12:38           ` Mark Rutland
2019-08-07 16:15           ` Rob Clark
2019-08-07 16:15             ` Rob Clark
2019-08-07 16:49             ` Mark Rutland
2019-08-07 16:49               ` Mark Rutland
2019-08-07 17:30               ` Rob Clark
2019-08-07 17:30                 ` Rob Clark
2019-08-08  7:59                 ` Christoph Hellwig
2019-08-08  7:59                   ` Christoph Hellwig
2019-08-08 16:44                   ` Rob Clark
2019-08-08 16:44                     ` Rob Clark
2019-08-09  8:18                     ` Christoph Hellwig
2019-08-09  8:18                       ` Christoph Hellwig
2019-08-08  7:58               ` Christoph Hellwig
2019-08-08  7:58                 ` Christoph Hellwig
2019-08-08 10:20                 ` Mark Rutland
2019-08-08 10:20                   ` Mark Rutland
2019-08-08 10:24                   ` Mark Rutland
2019-08-08 10:24                     ` Mark Rutland
2019-08-08 10:32                   ` Will Deacon
2019-08-08 10:32                     ` Will Deacon
2019-08-08  7:53           ` Christoph Hellwig [this message]
2019-08-08  7:53             ` Christoph Hellwig
2019-08-06 15:50     ` Christoph Hellwig
2019-08-06 15:50       ` Christoph Hellwig
2019-08-06 16:23       ` Rob Clark
2019-08-06 16:23         ` Rob Clark
2019-08-06 16:26         ` Rob Clark
2019-08-06 16:26           ` Rob Clark
2019-08-07  6:25         ` Christoph Hellwig
2019-08-07  6:25           ` Christoph Hellwig
2019-08-07  8:48           ` Daniel Vetter
2019-08-07  8:48             ` Daniel Vetter
2019-08-08  9:55             ` Christoph Hellwig
2019-08-08  9:55               ` Christoph Hellwig
2019-08-08 11:58               ` Daniel Vetter
2019-08-08 11:58                 ` Daniel Vetter
2019-08-08 11:58                 ` Daniel Vetter
2019-08-09  8:14                 ` Christoph Hellwig
2019-08-09  8:14                   ` Christoph Hellwig
2019-08-07 16:09           ` Rob Clark
2019-08-07 16:09             ` Rob Clark
2019-08-08 10:00             ` Christoph Hellwig
2019-08-08 10:00               ` Christoph Hellwig
2019-08-08 16:32               ` Rob Clark
2019-08-08 16:32                 ` Rob Clark

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