From: "Michel Dänzer" <michel@daenzer.net>
To: Ilija Hadzic <ihadzic@research.bell-labs.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2] drm/radeon/kms/blit: fix blit copy for very large buffers
Date: Thu, 02 Feb 2012 16:32:21 +0100 [thread overview]
Message-ID: <1328196741.24573.10.camel@thor.local> (raw)
In-Reply-To: <1328196384-28001-1-git-send-email-ihadzic@research.bell-labs.com>
On Don, 2012-02-02 at 10:26 -0500, Ilija Hadzic wrote:
> Evergreen and NI blit copy was broken if the buffer maps to a rectangle
> whose one dimension is 16384 (max dimension allowed by these chips).
> In the mainline kernel, the problem is exposed only when buffers are
> very large (1G), but it's still a problem. The problem could be exposed
> for smaller buffers if anyone modifies the algorithm for rectangle
> construction in r600_blit_create_rect() (the reason why someone would
> modify that algorithm is to tune the performance of buffer moves).
>
> The root cause was in i2f() function which only operated on range between
> 0 and 16383. Fix this by extending the range of i2f() function to 0 to
> 32767.
>
> While at it improve the function so that the range can be easily
> extended in the future (if it becomes necessary), cleanup lines
> over 80 characters, and replace in-line comments with one strategic
> comment that explains the crux of the function.
>
> Credits to michel@daenzer.net for pointing out the root cause of
> the bug.
>
> v2: Fix I2F_MAX_INPUT constant definition goof and warn only once
> if input argument is out of range. Edit the comment a little
> bit to avoid some linguistic confusion and make it look better
> in general.
>
> Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com>
Reviewed-by: Michel Dänzer <michel@daenzer.net>
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Debian, X and DRI developer
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prev parent reply other threads:[~2012-02-02 15:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-02 15:26 [PATCH v2] drm/radeon/kms/blit: fix blit copy for very large buffers Ilija Hadzic
2012-02-02 15:31 ` Alex Deucher
2012-02-02 15:40 ` Ilija Hadzic
2012-02-02 15:32 ` Michel Dänzer [this message]
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