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From: Daniel Vetter <daniel@ffwll.ch>
To: Simon Ser <contact@emersion.fr>
Cc: "jianxin.pan@amlogic.com" <jianxin.pan@amlogic.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"daniel@ffwll.ch" <daniel@ffwll.ch>,
	"linux-amlogic@lists.infradead.org"
	<linux-amlogic@lists.infradead.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v8 1/6] drm/fourcc: Add modifier definitions for describing Amlogic Video Framebuffer Compression
Date: Thu, 2 Jul 2020 15:18:34 +0200	[thread overview]
Message-ID: <20200702131834.GZ3278063@phenom.ffwll.local> (raw)
In-Reply-To: <8cBfZpkc4pHBLhihlvJMD_Hq1DEsNRcSY4Y8JaGwklMWcxiYzUMVEx7wH9f_DuCBMVUhXvOR0PcHVslILtKI2wdw79Nfih0N3VnrxfMQd08=@emersion.fr>

On Thu, Jul 02, 2020 at 09:23:11AM +0000, Simon Ser wrote:
> On Thursday, July 2, 2020 9:47 AM, Neil Armstrong <narmstrong@baylibre.com> wrote:
> 
> > Finally is also adds the Scatter Memory layout, meaning the header contains IOMMU
> > references to the compressed frames content to optimize memory access
> > and layout.
> >
> > In this mode, only the header memory address is needed, thus the content
> > memory organization is tied to the current producer execution and cannot
> > be saved/dumped neither transferrable between Amlogic SoCs supporting this
> > modifier.
> 
> Still not sure how to handle this one, since this breaks fundamental
> assumptions about modifiers.

I wonder whether we should require special allocations for these, and then
just outright reject mmap on these buffers. mmap on dma-buf isn't a
required feature.

That would make sure that userspace cannot look at them.

Also I'm kinda suspecting that there's not unlimited amounts of this magic
invisible storage available anyway.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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  reply	other threads:[~2020-07-02 13:18 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-02  7:47 [PATCH v8 0/6] drm/meson: add support for Amlogic Video FBC Neil Armstrong
2020-07-02  7:47 ` [PATCH v8 1/6] drm/fourcc: Add modifier definitions for describing Amlogic Video Framebuffer Compression Neil Armstrong
2020-07-02  9:23   ` Simon Ser
2020-07-02 13:18     ` Daniel Vetter [this message]
2020-07-02 13:34       ` Neil Armstrong
2020-07-02 14:15         ` Daniel Vetter
2020-07-02 15:11           ` Neil Armstrong
2020-07-02 18:03             ` Daniel Vetter
2020-07-02  7:47 ` [PATCH v8 2/6] drm/meson: add Amlogic Video FBC registers Neil Armstrong
2020-07-02  7:47 ` [PATCH v8 3/6] drm/meson: overlay: setup overlay for Amlogic FBC Neil Armstrong
2020-07-02  7:47 ` [PATCH v8 4/6] drm/meson: overlay: setup overlay for Amlogic FBC Memory Saving mode Neil Armstrong
2020-07-02  7:47 ` [PATCH v8 5/6] drm/meson: overlay: setup overlay for Amlogic FBC Scatter Memory layout Neil Armstrong
2020-07-02  7:47 ` [PATCH v8 6/6] drm/meson: crtc: handle commit of Amlogic FBC frames Neil Armstrong
2020-07-02 18:57 ` [PATCH v8 0/6] drm/meson: add support for Amlogic Video FBC Kevin Hilman

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