From: Tony Lindgren <tony@atomide.com> To: Tomi Valkeinen <tomi.valkeinen@ti.com>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Sebastian Reichel <sre@kernel.org>, dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, "H . Nikolaus Schaller" <hns@goldelico.com>, Merlijn Wajer <merlijn@wizzup.org> Subject: Re: [PATCH] drm/omap: gem: Fix tearing with BO_TILED Date: Wed, 8 Jan 2020 08:57:14 -0800 [thread overview] Message-ID: <20200108165714.GI5885@atomide.com> (raw) In-Reply-To: <20200106180631.GA30670@chinchilla> * Matthijs van Duin <matthijsvanduin@gmail.com> [200106 10:07]: > On Sun, Jan 05, 2020 at 12:37:04PM -0800, Tony Lindgren wrote: > > 4. The issue I'm seeing with stellarium on droid4 may be a stride > > issue as about one out of 3 or 4 frames is OK and aligning to > > 512 also fixes the issue maybe because it happens to make > > multiple frames align to 4096 > > Yeah if your buffers are 960 pixels wide (assuming the droid4's screen > is natively portrait) and 32bpp then 512-byte alignment suffices to > automatically make them 4KB alignment. Hmm sounds like I need to retest this. But doesn't 512-byte alignment only make the 960 pixels case 2KB aligned? > The most obvious thing I can think of that could do wrong is that it > might contiguously map the pages that cover each line, which is what > will happen if they use e.g. for_each_sg_page, but subsequently assume > that the stride in sgx virtual memory is ALIGN( width * cpp, PAGE_SIZE ) > without taking the offset of the buffer inside the mapping into account. OK > If each line is at most 4KB (i.e. 1024 pixels @ 32bpp) but each line > straddles an MMU page boundary, then the result would be that the even > lines of the frame are written to the top half of the buffer, causing it > to be scaled to 50% vertically, while the odd lines are "lost" (written > outside the buffer, either to a different buffer or unmapped tiler > memory). This sounds like what you described on irc? Yes this sounds like what I've been seeing. Regards, Tony
WARNING: multiple messages have this Message-ID (diff)
From: Tony Lindgren <tony@atomide.com> To: Tomi Valkeinen <tomi.valkeinen@ti.com>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Sebastian Reichel <sre@kernel.org>, dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, "H . Nikolaus Schaller" <hns@goldelico.com>, Merlijn Wajer <merlijn@wizzup.org> Subject: Re: [PATCH] drm/omap: gem: Fix tearing with BO_TILED Date: Wed, 8 Jan 2020 08:57:14 -0800 [thread overview] Message-ID: <20200108165714.GI5885@atomide.com> (raw) In-Reply-To: <20200106180631.GA30670@chinchilla> * Matthijs van Duin <matthijsvanduin@gmail.com> [200106 10:07]: > On Sun, Jan 05, 2020 at 12:37:04PM -0800, Tony Lindgren wrote: > > 4. The issue I'm seeing with stellarium on droid4 may be a stride > > issue as about one out of 3 or 4 frames is OK and aligning to > > 512 also fixes the issue maybe because it happens to make > > multiple frames align to 4096 > > Yeah if your buffers are 960 pixels wide (assuming the droid4's screen > is natively portrait) and 32bpp then 512-byte alignment suffices to > automatically make them 4KB alignment. Hmm sounds like I need to retest this. But doesn't 512-byte alignment only make the 960 pixels case 2KB aligned? > The most obvious thing I can think of that could do wrong is that it > might contiguously map the pages that cover each line, which is what > will happen if they use e.g. for_each_sg_page, but subsequently assume > that the stride in sgx virtual memory is ALIGN( width * cpp, PAGE_SIZE ) > without taking the offset of the buffer inside the mapping into account. OK > If each line is at most 4KB (i.e. 1024 pixels @ 32bpp) but each line > straddles an MMU page boundary, then the result would be that the even > lines of the frame are written to the top half of the buffer, causing it > to be scaled to 50% vertically, while the odd lines are "lost" (written > outside the buffer, either to a different buffer or unmapped tiler > memory). This sounds like what you described on irc? Yes this sounds like what I've been seeing. Regards, Tony _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-01-08 16:57 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-21 0:57 [PATCH] drm/omap: gem: Fix tearing with BO_TILED Tony Lindgren 2019-12-21 0:57 ` Tony Lindgren 2019-12-21 16:41 ` Tony Lindgren 2019-12-21 16:41 ` Tony Lindgren 2020-01-04 5:09 ` Matthijs van Duin 2020-01-04 5:09 ` Matthijs van Duin 2020-01-04 5:50 ` Tony Lindgren 2020-01-04 5:50 ` Tony Lindgren 2020-01-05 20:37 ` Tony Lindgren 2020-01-05 20:37 ` Tony Lindgren 2020-01-06 18:06 ` Matthijs van Duin 2020-01-06 18:06 ` Matthijs van Duin 2020-01-08 16:57 ` Tony Lindgren [this message] 2020-01-08 16:57 ` Tony Lindgren 2020-01-07 13:30 ` Tomi Valkeinen 2020-01-07 13:30 ` Tomi Valkeinen 2020-01-07 13:31 ` Tomi Valkeinen 2020-01-07 13:31 ` Tomi Valkeinen 2020-01-04 4:52 ` Matthijs van Duin 2020-01-04 4:52 ` Matthijs van Duin 2020-01-04 5:53 ` Tony Lindgren 2020-01-04 5:53 ` Tony Lindgren
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