From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: "Zanoni, Paulo R" <paulo.r.zanoni@intel.com>,
"ville.syrjala@linux.intel.com" <ville.syrjala@linux.intel.com>
Cc: "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH igt 1/3] lib/igt_fb: also call __gem_set_tiling for Y tiling
Date: Mon, 1 Feb 2016 17:44:42 +0000 [thread overview]
Message-ID: <56AF998A.7040101@linux.intel.com> (raw)
In-Reply-To: <1454346984.2538.14.camel@intel.com>
On 01/02/16 17:16, Zanoni, Paulo R wrote:
> Em Sex, 2016-01-29 às 21:06 +0200, Ville Syrjälä escreveu:
>> On Fri, Jan 29, 2016 at 04:46:30PM -0200, Paulo Zanoni wrote:
>>> The interesting thing is that if we don't do this, we still get a
>>> Y tiled framebuffer, but there won't be a fence around it, which
>>> makes
>>> the GTT mmaps less interesting. Is this a Kernel bug?
>>
>> I think some tests currently depend on not having a fence for Y tiled
>> fbs. So this could break stuff.
>
> Do you have any additional information that could help me discover
> which ones? A quick look on the IGT tests mentioning tiling didn't
> point anything obvious.
>
> Besides, I think it's probably not a good idea to have such a high
> level helper function behaving differently depending on the tiling
> type, I'd vote to either call set_tiling on both or on none.
Noticed the thread by accident. :)
I can't help with the question of which tests might be affected by this.
Some low level ones like kms_addfb don't use the fb helpers so they
shouldn't be. Can't remember if any other would be.
But just a little bit of background:
Basically with the introduction of Y tiled (and Yf) scanout in Gen9 we
have forked the path and destroyed the coupling between obj->tiling and
framebuffer tiling.
The X special casing in create_bo_for_fb is for compatibility with old
userspace, but going forward it was decided fb modifiers should be used
to tell the driver about tiling and get/set_tiling ioctl is about
fencing and only that.
Paths implemented in IGT back then were rendering to Y and Yf tiling fbs
via a temporary linear surface which is then blitted (blit?) to the real
fb obj. (With the blitter doing the appropriate transformation.)
So in that respect adding Y tiling to create_bo_for_fb would be wrong
because it is not aligned with the above, and also you cannot support Yf
this way at all.
But I do agree this creates a problem for some use cases within the IGT
since the fb and backing obj are created atomically and once that is
done you cannot fiddle with obj->tiling (aka fencing).
Regards,
Tvrtko
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next prev parent reply other threads:[~2016-02-01 17:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-29 18:46 [PATCH igt 1/3] lib/igt_fb: also call __gem_set_tiling for Y tiling Paulo Zanoni
2016-01-29 18:46 ` [PATCH igt 2/3] lib/igt_draw: add support " Paulo Zanoni
2016-02-10 8:22 ` Daniel Vetter
2016-01-29 18:46 ` [PATCH igt 3/3] tests/kms_draw_crc: " Paulo Zanoni
2016-01-29 19:06 ` [PATCH igt 1/3] lib/igt_fb: also call __gem_set_tiling " Ville Syrjälä
2016-02-01 17:16 ` Zanoni, Paulo R
2016-02-01 17:23 ` Ville Syrjälä
2016-02-01 17:44 ` Tvrtko Ursulin [this message]
2016-02-01 17:57 ` Ville Syrjälä
2016-02-02 9:34 ` Tvrtko Ursulin
2016-02-10 8:20 ` Daniel Vetter
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