linux-dev/drivers/video/fbdev/core/tileblit.c, branch linus/master

Revert "fbdev: Garbage collect fbdev scrolling acceleration, part 1 (from TODO list)"

2022-02-02T14:14:56Z

This reverts commit b3ec8cdf457e5e63d396fe1346cc788cf7c1b578. Revert the second (of 2) commits which disabled scrolling acceleration in fbcon/fbdev. It introduced a regression for fbdev-supported graphic cards because of the performance penalty by doing screen scrolling by software instead of using the existing graphic card 2D hardware acceleration. Console scrolling acceleration was disabled by dropping code which checked at runtime the driver hardware capabilities for the BINFO_HWACCEL_COPYAREA or FBINFO_HWACCEL_FILLRECT flags and if set, it enabled scrollmode SCROLL_MOVE which uses hardware acceleration to move screen contents. After dropping those checks scrollmode was hard-wired to SCROLL_REDRAW instead, which forces all graphic cards to redraw every character at the new screen position when scrolling. This change effectively disabled all hardware-based scrolling acceleration for ALL drivers, because now all kind of 2D hardware acceleration (bitblt, fillrect) in the drivers isn't used any longer. The original commit message mentions that only 3 DRM drivers (nouveau, omapdrm and gma500) used hardware acceleration in the past and thus code for checking and using scrolling acceleration is obsolete. This statement is NOT TRUE, because beside the DRM drivers there are around 35 other fbdev drivers which depend on fbdev/fbcon and still provide hardware acceleration for fbdev/fbcon. The original commit message also states that syzbot found lots of bugs in fbcon and thus it's "often the solution to just delete code and remove features". This is true, and the bugs - which actually affected all users of fbcon, including DRM - were fixed, or code was dropped like e.g. the support for software scrollback in vgacon (commit 973c096f6a85). So to further analyze which bugs were found by syzbot, I've looked through all patches in drivers/video which were tagged with syzbot or syzkaller back to year 2005. The vast majority fixed the reported issues on a higher level, e.g. when screen is to be resized, or when font size is to be changed. The few ones which touched driver code fixed a real driver bug, e.g. by adding a check. But NONE of those patches touched code of either the SCROLL_MOVE or the SCROLL_REDRAW case. That means, there was no real reason why SCROLL_MOVE had to be ripped-out and just SCROLL_REDRAW had to be used instead. The only reason I can imagine so far was that SCROLL_MOVE wasn't used by DRM and as such it was assumed that it could go away. That argument completely missed the fact that SCROLL_MOVE is still heavily used by fbdev (non-DRM) drivers. Some people mention that using memcpy() instead of the hardware acceleration is pretty much the same speed. But that's not true, at least not for older graphic cards and machines where we see speed decreases by factor 10 and more and thus this change leads to console responsiveness way worse than before. That's why the original commit is to be reverted. By reverting we reintroduce hardware-based scrolling acceleration and fix the performance regression for fbdev drivers. There isn't any impact on DRM when reverting those patches. Signed-off-by: Helge Deller Acked-by: Geert Uytterhoeven Acked-by: Sven Schnelle Cc: stable@vger.kernel.org # v5.16+ Signed-off-by: Helge Deller Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220202135531.92183-2-deller@gmx.de

fbdev: Garbage collect fbdev scrolling acceleration, part 1 (from TODO list)

2021-10-13T13:29:23Z

Scroll acceleration is disabled in fbcon by hard-wiring p->scrollmode = SCROLL_REDRAW. Remove the obsolete code in fbcon.c and fbdev/core/ Signed-off-by: Claudio Suarez Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/YVXTYqszZix9TxjJ@gineta.localdomain

fbcon: Drop EXPORT_SYMBOL

2020-11-17T10:00:43Z

Every since commit 6104c37094e729f3d4ce65797002112735d49cd1 Author: Daniel Vetter Date: Tue Aug 1 17:32:07 2017 +0200 fbcon: Make fbcon a built-time depency for fbdev these are no longer distinct loadable modules, so exporting symbols is kinda pointless. Acked-by: Thomas Zimmermann Signed-off-by: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: Daniel Vetter Cc: Tetsuo Handa Cc: Helge Deller Cc: Peilin Ye Link: https://patchwork.freedesktop.org/patch/msgid/20201029101428.4058311-2-daniel.vetter@ffwll.ch

fbcon: Avoid using FNTCHARCNT() and hard-coded built-in font charcount

2020-11-16T15:33:12Z

For user-provided fonts, the framebuffer layer is using a magic negative-indexing macro, FNTCHARCNT(), to keep track of their number of characters: #define FNTCHARCNT(fd) (((int *)(fd))[-3]) For built-in fonts, it is using hard-coded values (256). This results in something like the following: map.length = (ops->p->userfont) ? FNTCHARCNT(ops->p->fontdata) : 256; This is unsatisfactory. In fact, there is already a `charcount` field in our virtual console descriptor (see `struct console_font` inside `struct vc_data`), let us use it: map.length = vc->vc_font.charcount; Recently we added a `charcount` field to `struct font_desc`. Use it to set `vc->vc_font.charcount` properly. The idea is: - We only use FNTCHARCNT() on `vc->vc_font.data` and `p->fontdata`. Assume FNTCHARCNT() is working as intended; - Whenever `vc->vc_font.data` is set, also set `vc->vc_font.charcount` properly; - We can now replace `FNTCHARCNT(vc->vc_font.data)` with `vc->vc_font.charcount`; - Since `p->fontdata` always point to the same font data buffer with `vc->vc_font.data`, we can also replace `FNTCHARCNT(p->fontdata)` with `vc->vc_font.charcount`. In conclusion, set `vc->vc_font.charcount` properly in fbcon_startup(), fbcon_init(), fbcon_set_disp() and fbcon_do_set_font(), then replace FNTCHARCNT() with `vc->vc_font.charcount`. No more if-else between negative-indexing macros and hard-coded values. Do not include in fbcon_rotate.c and tileblit.c, since they no longer need it. Depends on patch "Fonts: Add charcount field to font_desc". Suggested-by: Daniel Vetter Signed-off-by: Peilin Ye Reviewed-by: Greg Kroah-Hartman Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/e460a5780e54e3022661d5f09555144583b4cc59.1605169912.git.yepeilin.cs@gmail.com

Merge tag 'drm-misc-fixes-2020-10-01' of git://anongit.freedesktop.org/drm/drm-misc into drm-fixes

2020-10-06T02:38:28Z

drm-misc-fixes for v5.9: - Small doc fix. - Re-add FB_ARMCLCD for android. - Fix global-out-of-bounds read in fbcon_get_font(). Signed-off-by: Dave Airlie From: Maarten Lankhorst Link: https://patchwork.freedesktop.org/patch/msgid/8585daa2-fcbc-3924-ac4f-e7b5668808e0@linux.intel.com

fbdev, newport_con: Move FONT_EXTRA_WORDS macros into linux/font.h

2020-09-25T08:28:18Z

drivers/video/console/newport_con.c is borrowing FONT_EXTRA_WORDS macros from drivers/video/fbdev/core/fbcon.h. To keep things simple, move all definitions into . Since newport_con now uses four extra words, initialize the fourth word in newport_set_font() properly. Cc: stable@vger.kernel.org Signed-off-by: Peilin Ye Reviewed-by: Greg Kroah-Hartman Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/7fb8bc9b0abc676ada6b7ac0e0bd443499357267.1600953813.git.yepeilin.cs@gmail.com

fbcon: remove now unusued 'softback_lines' cursor() argument

2020-09-14T17:06:15Z

Since the softscroll code got removed, this argument is always zero and makes no sense any more. Tested-by: Yuan Ming Tested-by: Willy Tarreau Reviewed-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds

vt: use newly defined CUR_* macros

2020-06-24T15:08:33Z

We defined macros for all the magic constants in the previous patch. So let us use the macro in the code now. No functional change intended. Signed-off-by: Jiri Slaby Cc: Thomas Winischhofer Cc: Bartlomiej Zolnierkiewicz Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: linux-usb@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-fbdev@vger.kernel.org Cc: linux-parisc@vger.kernel.org Acked-by: Helge Deller Link: https://lore.kernel.org/r/20200615074910.19267-26-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

vc: separate state

2020-06-24T15:08:30Z

There are two copies of some members of struct vc_data. This is because we need to save them and restore later. Move these memebers to a separate structure called vc_state. So now instead of members like: vc_x, vc_y and vc_saved_x, vc_saved_y we have state and saved_state (of type: struct vc_state) containing state.x, state.y and saved_state.x, saved_state.y This change: * makes clear what is saved & restored * eases save & restore by using memcpy (see save_cur and restore_cur) Finally, we document the newly added struct vc_state using kernel-doc. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20200615074910.19267-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

fbcon: add fbcon=margin: command line option

2017-08-18T17:56:40Z

This adds a new command line option to select the fbcon margin color. The motivation for this is screens where black does not blend into the physical surroundings of the screen. For example, using an LCD (not the backlit kind), white text on a black background is hard to read, so inverting the colors is preferred. However, when you do this, most of the screen is filled with white but the margins are still filled with black. This makes a big, black, backwards 'L' on the screen. By setting fbcon=margin:7, the margins will be filled with white and the LCD looks as expected. Signed-off-by: David Lechner [b.zolnierkie: ported over fbcon changes] Signed-off-by: Bartlomiej Zolnierkiewicz