From: Roman Stratiienko <roman.stratiienko@globallogic.com>
To: Maxime Ripard <mripard@kernel.org>
Cc: "Jernej Škrabec" <jernej.skrabec@siol.net>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: drm/sun4i: Add missing pixel formats to the vi layer
Date: Fri, 20 Sep 2019 13:14:30 +0300 [thread overview]
Message-ID: <CAODwZ7sJ9g4fycde5Yk1sRYW6WuNtsgXOf34GJMma0rKMyc0QQ@mail.gmail.com> (raw)
In-Reply-To: <20190920062020.zyt5ng6cxtu6muye@gilmour>
On Fri, Sep 20, 2019 at 9:20 AM Maxime Ripard <mripard@kernel.org> wrote:
>
> On Thu, Sep 19, 2019 at 08:53:10PM +0200, Jernej Škrabec wrote:
> > Dne sreda, 18. september 2019 ob 13:05:41 CEST je
> > roman.stratiienko@globallogic.com napisal(a):
> > > From: Roman Stratiienko <roman.stratiienko@globallogic.com>
> > >
> > > According to Allwinner DE2.0 Specification REV 1.0, vi layer supports the
> > > following pixel formats: ABGR_8888, ARGB_8888, BGRA_8888, RGBA_8888
> >
> > It's true that DE2 VI layers support those formats, but it wouldn't change
> > anything because alpha blending is not supported by those planes. These
> > formats were deliberately left out because their counterparts without alpha
> > exist, for example ABGR8888 <-> XBGR8888. It would also confuse user, which
> > would expect that alpha blending works if format with alpha channel is
> > selected.
>
> I'm not too familiar with the DE2 code, but why is alpha not working
> if the VI planes support formats with alpha?
Good question. It mentioned in the datasheet
https://linux-sunxi.org/images/7/7b/Allwinner_DE2.0_Spec_V1.0.pdf
on page 95: "All ui layers' alpha is useless"
And my experiments proves it.
My assumption that vi uses post-processing that cuts out alpha values.
>
> Thanks!
> Maxime
--
Best regards,
Roman Stratiienko
Global Logic Inc.
next prev parent reply other threads:[~2019-09-20 10:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-18 11:05 [PATCH] drm/sun4i: Add missing pixel formats to the vi layer roman.stratiienko
2019-09-19 18:53 ` Jernej Škrabec
2019-09-20 6:20 ` Maxime Ripard
2019-09-20 10:14 ` Roman Stratiienko [this message]
2019-09-20 20:22 ` Roman Stratiienko
2019-09-20 20:31 ` Jernej Škrabec
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