From: Thomas Zimmermann <tzimmermann@suse.de>
To: daniel@ffwll.ch, noralf@tronnes.org, airlied@linux.ie,
rong.a.chen@intel.com, feng.tang@intel.com, ying.huang@intel.com,
sean@poorly.run, maxime.ripard@bootlin.com,
maarten.lankhorst@linux.intel.com
Cc: Thomas Zimmermann <tzimmermann@suse.de>, dri-devel@lists.freedesktop.org
Subject: [PATCH 0/3] drm/vram-helper: Fix performance regression in fbdev
Date: Thu, 1 Aug 2019 13:56:39 +0200 [thread overview]
Message-ID: <20190801115642.21231-1-tzimmermann@suse.de> (raw)
Generic fbdev emulation maps and unmaps the console BO for updating it's
content from the shadow buffer. Drivers using VRAM helpers may see reduced
performance as the mapping operations can create significant overhead.
A report of this problem is at [1].
This patch set fixes the problem by adding a ref counter to the GEM
VRAM buffers' kmap operation, and keeping the fbdev's console buffer
mapped while the console is being displayed. These changes avoids the
frequent mappings in the fbdev code. The drivers, ast and mgag200,
maps the console's buffer when it becomes visible and the fbdev code
reuses this mapping. The original fbdev code in ast and mgag200 used
the same optimization.
[1] https://lists.freedesktop.org/archives/dri-devel/2019-July/228663.html
Thomas Zimmermann (3):
drm/vram-helpers: Add kmap ref-counting to GEM VRAM objects
drm/ast: Map fbdev framebuffer while it's being displayed
drm/mgag200: Map fbdev framebuffer while it's being displayed
drivers/gpu/drm/ast/ast_mode.c | 20 +++++++
drivers/gpu/drm/drm_gem_vram_helper.c | 74 +++++++++++++++++++-------
drivers/gpu/drm/mgag200/mgag200_mode.c | 21 ++++++++
include/drm/drm_gem_vram_helper.h | 13 +++++
4 files changed, 110 insertions(+), 18 deletions(-)
--
2.22.0
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next reply other threads:[~2019-08-01 11:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 11:56 Thomas Zimmermann [this message]
2019-08-01 11:56 ` [PATCH 1/3] drm/vram-helpers: Add kmap ref-counting to GEM VRAM objects Thomas Zimmermann
2019-08-01 11:56 ` [PATCH 2/3] drm/ast: Map fbdev framebuffer while it's being displayed Thomas Zimmermann
2019-08-01 11:56 ` [PATCH 3/3] drm/mgag200: " Thomas Zimmermann
-- strict thread matches above, loose matches on Subject: below --
2019-08-01 11:50 [PATCH 0/3] drm/vram-helper: Fix performance regression in fbdev Thomas Zimmermann
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