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Date:   Tue, 18 Aug 2020 10:27:03 +0200
From:   Gerd Hoffmann <kraxel@redhat.com>
To:     Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>
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Subject: Re: [PATCH 1/2] drm: allow limiting the scatter list size.
Message-ID: <20200818082703.7z6fcvoymiqow5kw@sirius.home.kraxel.org>
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 <20200818074828.9509-2-kraxel@redhat.com>
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On Tue, Aug 18, 2020 at 09:57:59AM +0200, Christian K?nig wrote:
> Am 18.08.20 um 09:48 schrieb Gerd Hoffmann:
> > Add max_segment argument to drm_prime_pages_to_sg().  When set pass it
> > through to the __sg_alloc_table_from_pages() call, otherwise use
> > SCATTERLIST_MAX_SEGMENT.
> > 
> > Also add max_segment field to gem objects and pass it to
> > drm_prime_pages_to_sg() calls in drivers and helpers.
> > 
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> I'm missing an explanation why this should be useful (it certainly is).

virtio-gpu needs this to work properly with SEV (see patch 2/2 of this
series).

> And the maximum segment size seems misplaced in the GEM object. This is
> usually a property of the device or even completely constant.

Placing it in drm_device instead would indeed work for virtio-gpu, so I
guess you are suggesting that instead?

take care,
  Gerd