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author | Thomas Zimmermann <tzimmermann@suse.de> | 2022-04-29 13:08:31 +0300 |
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committer | Thomas Zimmermann <tzimmermann@suse.de> | 2022-05-03 17:04:22 +0300 |
commit | 56c134f7f1b58be08bdb0ca8372474a4a5165f31 (patch) | |
tree | 9d03ef69c09f34f93aa9258562728ec28fdd1222 /drivers/staging/fbtft | |
parent | 5905585103276b7c14bb9a7de4b575216cb6dac4 (diff) | |
download | linux-56c134f7f1b58be08bdb0ca8372474a4a5165f31.tar.xz |
fbdev: Track deferred-I/O pages in pageref struct
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
Diffstat (limited to 'drivers/staging/fbtft')
-rw-r--r-- | drivers/staging/fbtft/fbtft-core.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c index d4e14f7c9d57..e9662822e1ef 100644 --- a/drivers/staging/fbtft/fbtft-core.c +++ b/drivers/staging/fbtft/fbtft-core.c @@ -326,7 +326,7 @@ static void fbtft_deferred_io(struct fb_info *info, struct list_head *pagelist) { struct fbtft_par *par = info->par; unsigned int dirty_lines_start, dirty_lines_end; - struct page *page; + struct fb_deferred_io_pageref *pageref; unsigned long index; unsigned int y_low = 0, y_high = 0; int count = 0; @@ -340,7 +340,8 @@ static void fbtft_deferred_io(struct fb_info *info, struct list_head *pagelist) spin_unlock(&par->dirty_lock); /* Mark display lines as dirty */ - list_for_each_entry(page, pagelist, lru) { + list_for_each_entry(pageref, pagelist, list) { + struct page *page = pageref->page; count++; index = page->index << PAGE_SHIFT; y_low = index / info->fix.line_length; |