Use pageref->offset instead of page->index for deferred-I/O writeback
where appropriate. Distinguishes between file-mapping offset and video-
memory offset. While at it, also remove unnecessary references to
struct page.
Fbdev's deferred-I/O code uses the two related page->index and
pageref->offset. The former is the page offset in the mapped file,
the latter is the byte offset in the video memory (or fbdev screen
buffer). It's the same value for fbdev drivers, but for DRM the values
can be different. Because GEM buffer objects are mapped at an offset
in the DRM device file, page->index has this offset added to it as well.
We currently don't hit this case in DRM, because all affected mappings
of GEM memory are performed with an internal, intermediate shadow buffer.
The value of page->index is required by page_mkclean(), which we
call to reset the mappings during the writeback phase of the deferred
I/O. The value of pageref->offset is for conveniently getting an offset
into video memory in fb helpers.
v4:
* fix commit message (Javier)
Suggested-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100834.18898-6-tzimmermann@suse.de
Rename various instances of pagelist to pagereflist. The list now
stores pageref structures, so the new name is more appropriate.
In their write-back helpers, several fbdev drivers refer to the
pageref list in struct fb_deferred_io instead of using the one
supplied as argument to the function. Convert them over to the
supplied one. It's the same instance, so no change of behavior
occurs.
v4:
* fix commit message (Javier)
Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100834.18898-5-tzimmermann@suse.de
Store the per-page state for fbdev's deferred I/O in struct
fb_deferred_io_pageref. Maintain a list of pagerefs for the pages
that have to be written back to video memory. Update all affected
drivers.
As with pages before, fbdev acquires a pageref when an mmaped page
of the framebuffer is being written to. It holds the pageref in a
list of all currently written pagerefs until it flushes the written
pages to video memory. Writeback occurs periodically. After writeback
fbdev releases all pagerefs and builds up a new dirty list until the
next writeback occurs.
Using pagerefs has a number of benefits.
For pages of the framebuffer, the deferred I/O code used struct
page.lru as an entry into the list of dirty pages. The lru field is
owned by the page cache, which makes deferred I/O incompatible with
some memory pages (e.g., most notably DRM's GEM SHMEM allocator).
struct fb_deferred_io_pageref now provides an entry into a list of
dirty framebuffer pages, freeing lru for use with the page cache.
Drivers also assumed that struct page.index is the page offset into
the framebuffer. This is not true for DRM buffers, which are located
at various offset within a mapped area. struct fb_deferred_io_pageref
explicitly stores an offset into the framebuffer. struct page.index
is now only the page offset into the mapped area.
These changes will allow DRM to use fbdev deferred I/O without an
intermediate shadow buffer.
v3:
* use pageref->offset for sorting
* fix grammar in comment
v2:
* minor fixes in commit message
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100834.18898-3-tzimmermann@suse.de
The fbdev mmap function fb_mmap() unconditionally overrides the
driver's implementation if deferred I/O has been activated. This
makes it hard to implement mmap with anything but a vmalloc()'ed
software buffer. That is specifically a problem for DRM, where
video memory is maintained by a memory manager.
Leave the mmap handling to drivers and expect them to call the
helper for deferred I/O by thmeselves.
v4:
* unlock mm_lock in fb_mmap() error path (Dan)
v3:
* fix warning if fb_mmap is missing (kernel test robot)
v2:
* print a helpful error message if the defio setup is
incorrect (Javier)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100834.18898-2-tzimmermann@suse.de
Fbdev's deferred I/O sorts all dirty pages by default, which incurs a
significant overhead. Make the sorting step optional and update the few
drivers that require it. Use a FIFO list by default.
Most fbdev drivers with deferred I/O build a bounding rectangle around
the dirty pages or simply flush the whole screen. The only two affected
DRM drivers, generic fbdev and vmwgfx, both use a bounding rectangle.
In those cases, the exact order of the pages doesn't matter. The other
drivers look at the page index or handle pages one-by-one. The patch
sets the sort_pagelist flag for those, even though some of them would
probably work correctly without sorting. Driver maintainers should update
their driver accordingly.
Sorting pages by memory offset for deferred I/O performs an implicit
bubble-sort step on the list of dirty pages. The algorithm goes through
the list of dirty pages and inserts each new page according to its
index field. Even worse, list traversal always starts at the first
entry. As video memory is most likely updated scanline by scanline, the
algorithm traverses through the complete list for each updated page.
For example, with 1024x768x32bpp each page covers exactly one scanline.
Writing a single screen update from top to bottom requires updating
768 pages. With an average list length of 384 entries, a screen update
creates (768 * 384 =) 294912 compare operation.
Fix this by making the sorting step opt-in and update the few drivers
that require it. All other drivers work with unsorted page lists. Pages
are appended to the list. Therefore, in the common case of writing the
framebuffer top to bottom, pages are still sorted by offset, which may
have a positive effect on performance.
Playing a video [1] in mplayer's benchmark mode shows the difference
(i7-4790, FullHD, simpledrm, kernel with debugging).
mplayer -benchmark -nosound -vo fbdev ./big_buck_bunny_720p_stereo.ogg
With sorted page lists:
BENCHMARKs: VC: 32.960s VO: 73.068s A: 0.000s Sys: 2.413s = 108.441s
BENCHMARK%: VC: 30.3947% VO: 67.3802% A: 0.0000% Sys: 2.2251% = 100.0000%
With unsorted page lists:
BENCHMARKs: VC: 31.005s VO: 42.889s A: 0.000s Sys: 2.256s = 76.150s
BENCHMARK%: VC: 40.7156% VO: 56.3219% A: 0.0000% Sys: 2.9625% = 100.0000%
VC shows the overhead of video decoding, VO shows the overhead of the
video output. Using unsorted page lists reduces the benchmark's run time
by ~32s/~25%.
v2:
* Make sorted pagelists the special case (Sam)
* Comment on drivers' use of pagelist (Sam)
* Warn about the overhead in comment
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://download.blender.org/peach/bigbuckbunny_movies/big_buck_bunny_720p_stereo.ogg # [1]
Link: https://patchwork.freedesktop.org/patch/msgid/20220211094640.21632-3-tzimmermann@suse.de
Now that the fbops member of struct fb_info is const, we can start
making the ops const as well.
This does not cover all drivers; some actually modify the fbops struct,
for example to adjust for different configurations, and others do more
involved things that I'd rather not touch in practically obsolete
drivers. Mostly this is the low hanging fruit where we can add "const"
and be done with it.
v3:
- un-constify atyfb, mb862xx, nvidia and uvesabf (0day)
v2:
- fix typo (Christophe de Dinechin)
- use "static const" instead of "const static" in mx3fb.c
- also constify smscufx.c
Cc: linux-fbdev@vger.kernel.org
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ce67f14435f3af498f2e8bf35ce4be11f7504132.1575390740.git.jani.nikula@intel.com
We have requested the firmware and it was loaded but we missed releasing
it both on success and error.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
static code analysis from cppcheck reports:
[drivers/video/fbdev/broadsheetfb.c:673]:
(error) Memory leak: sector_buffer
sector_buffer is not being kfree'd on each call to
broadsheet_spiflash_rewrite_sector(), so free it.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
The drivers/video directory is a mess. It contains generic video related
files, directories for backlight, console, linux logo, lots of fbdev
device drivers, fbdev framework files.
Make some order into the chaos by creating drivers/video/fbdev
directory, and move all fbdev related files there.
No functionality is changed, although I guess it is possible that some
subtle Makefile build order related issue could be created by this
patch.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Thomas Zimmermann