linux-kernel - Re: [PATCH 0/3] drm: omapdrm: Fix excessive GEM buffers DMM/CMA usage

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Date:   Wed, 16 Feb 2022 09:10:29 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>, tomba@...nel.org,
        airlied@...ux.ie, daniel@...ll.ch
Cc:     tony@...mide.com, merlijn@...zup.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH 0/3] drm: omapdrm: Fix excessive GEM buffers DMM/CMA usage

Hi

Am 19.01.22 um 11:23 schrieb Ivaylo Dimitrov:
> This patch series fixes excessive DMM or CMA usage of GEM buffers leading to
> various runtime allocation failures. The series enables daily usage of devices
> without exausting limited resources like CMA or DMM space if GPU rendering is
> needed.
> 
> The first patch doesn't bring any functional changes, it just moves some
> TILER/DMM related code to a separate function, to simplify the review of the
> next two patches.
> 
> The second patch allows off-CPU rendering to non-scanout buffers. Without that
> patch, it is basically impossible to use the driver allocated GEM buffers on
> OMAP3 for anything else but a basic CPU rendered examples as if we want GPU
> rendering, we must allocate buffers as scanout buffers, which are CMA allocated.
> CMA soon gets fragmented and we start seeing allocation failures. Such failres
> in Xorg cannot be handeled gracefully, so the system is basically unusable.
> 
> Third patch fixes similar issue on OMAP4/5, where DMM/TILER spaces get
> fragmented with time, leading to allocation failures.
> 
> Series were tested on Motolola Droid4 and Nokia N900, with OMAP DDX and
> PVR EXA from https://github.com/maemo-leste/xf86-video-omap
> 
> Ivaylo Dimitrov (3):
>    drm: omapdrm: simplify omap_gem_pin
>    drm: omapdrm: Support exporting of non-contiguous GEM BOs
>    drm: omapdrm: Do no allocate non-scanout GEMs through DMM/TILER

With the little expertise I have with omapdrm:

Acked-by: Thomas Zimmermann <tzimmermann@...e.de>

> 
>   drivers/gpu/drm/omapdrm/omap_gem.c        | 198 +++++++++++++++++-------------
>   drivers/gpu/drm/omapdrm/omap_gem.h        |   3 +-
>   drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c |   5 +-
>   3 files changed, 116 insertions(+), 90 deletions(-)
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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