linux-stable.git/drivers/video/fbdev, branch linux-6.14.y

fbdev: core: tileblit: Implement missing margin clearing for tileblit

2025-05-29T09:12:26+00:00

[ Upstream commit 76d3ca89981354e1f85a3e0ad9ac4217d351cc72 ]

I was wondering why there's garbage at the bottom of the screen when
tile blitting is used with an odd mode like 1080, 600 or 200. Sure there's
only space for half a tile but the same area is clean when the buffer
is bitmap.

Then later I found that it's supposed to be cleaned but that's not
implemented. So I took what's in bitblit and adapted it for tileblit.

This implementation was tested for both the horizontal and vertical case,
and now does the same as what's done for bitmap buffers.

If anyone is interested to reproduce the problem then I could bet that'd
be on a S3 or Ark. Just set up a mode with an odd line count and make
sure that the virtual size covers the complete tile at the bottom. E.g.
for 600 lines that's 608 virtual lines for a 16 tall tile. Then the
bottom area should be cleaned.

For the right side it's more difficult as there the drivers won't let an
odd size happen, unless the code is modified. But once it reports back a
few pixel columns short then fbcon won't use the last column. With the
patch that column is now clean.

Btw. the virtual size should be rounded up by the driver for both axes
(not only the horizontal) so that it's dividable by the tile size.
That's a driver bug but correcting it is not in scope for this patch.

Implement missing margin clearing for tileblit

Signed-off-by: Zsolt Kajtar 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbcon: Use correct erase colour for clearing in fbcon

2025-05-29T09:12:25+00:00

[ Upstream commit 892c788d73fe4a94337ed092cb998c49fa8ecaf4 ]

The erase colour calculation for fbcon clearing should use get_color instead
of attr_col_ec, like everything else. The latter is similar but is not correct.
For example it's missing the depth dependent remapping and doesn't care about
blanking.

The problem can be reproduced by setting up the background colour to grey
(vt.color=0x70) and having an fbcon console set to 2bpp (4 shades of gray).
Now the background attribute should be 1 (dark gray) on the console.

If the screen is scrolled when pressing enter in a shell prompt at the bottom
line then the new line is cleared using colour 7 instead of 1. That's not
something fillrect likes (at 2bbp it expect 0-3) so the result is interesting.

This patch switches to get_color with vc_video_erase_char to determine the
erase colour from attr_col_ec. That makes the latter function redundant as
no other users were left.

Use correct erase colour for clearing in fbcon

Signed-off-by: Zsolt Kajtar 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: fsl-diu-fb: add missing device_remove_file()

2025-05-29T09:12:25+00:00

[ Upstream commit 86d16cd12efa547ed43d16ba7a782c1251c80ea8 ]

Call device_remove_file() when driver remove.

Signed-off-by: Shixiong Ou 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: omapfb: Add 'plane' value check

2025-04-20T08:22:41+00:00

[ Upstream commit 3e411827f31db7f938a30a3c7a7599839401ec30 ]

Function dispc_ovl_setup is not intended to work with the value OMAP_DSS_WB
of the enum parameter plane.

The value of this parameter is initialized in dss_init_overlays and in the
current state of the code it cannot take this value so it's not a real
problem.

For the purposes of defensive coding it wouldn't be superfluous to check
the parameter value, because some functions down the call stack process
this value correctly and some not.

For example, in dispc_ovl_setup_global_alpha it may lead to buffer
overflow.

Add check for this value.

Found by Linux Verification Center (linuxtesting.org) with SVACE static
analysis tool.

Signed-off-by: Leonid Arapov 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: sm501fb: Add some geometry checks.

2025-04-10T12:44:20+00:00

[ Upstream commit aee50bd88ea5fde1ff4cc021385598f81a65830c ]

Added checks for xoffset, yoffset settings.
Incorrect settings of these parameters can lead to errors
in sm501fb_pan_ functions.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 5fc404e47bdf ("[PATCH] fb: SM501 framebuffer driver")
Signed-off-by: Danila Chernetsov 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: au1100fb: Move a variable assignment behind a null pointer check

2025-04-10T12:44:20+00:00

[ Upstream commit 2df2c0caaecfd869b49e14f2b8df822397c5dd7f ]

The address of a data structure member was determined before
a corresponding null pointer check in the implementation of
the function “au1100fb_setmode”.

This issue was detected by using the Coccinelle software.

Fixes: 3b495f2bb749 ("Au1100 FB driver uplift for 2.6.")
Signed-off-by: Markus Elfring 
Acked-by: Uwe Kleine-König 
Signed-off-by: Helge Deller 
Signed-off-by: Sasha Levin

fbdev: hyperv_fb: Allow graceful removal of framebuffer

2025-03-09T23:56:29+00:00

When a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to
release the framebuffer forcefully. If this framebuffer is in use it
produce the following WARN and hence this framebuffer is never released.

[   44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40
< snip >
[   44.111289] Call Trace:
[   44.111290]  
[   44.111291]  ? show_regs+0x6c/0x80
[   44.111295]  ? __warn+0x8d/0x150
[   44.111298]  ? framebuffer_release+0x2c/0x40
[   44.111300]  ? report_bug+0x182/0x1b0
[   44.111303]  ? handle_bug+0x6e/0xb0
[   44.111306]  ? exc_invalid_op+0x18/0x80
[   44.111308]  ? asm_exc_invalid_op+0x1b/0x20
[   44.111311]  ? framebuffer_release+0x2c/0x40
[   44.111313]  ? hvfb_remove+0x86/0xa0 [hyperv_fb]
[   44.111315]  vmbus_remove+0x24/0x40 [hv_vmbus]
[   44.111323]  device_remove+0x40/0x80
[   44.111325]  device_release_driver_internal+0x20b/0x270
[   44.111327]  ? bus_find_device+0xb3/0xf0

Fix this by moving the release of framebuffer and assosiated memory
to fb_ops.fb_destroy function, so that framebuffer framework handles
it gracefully.

While we fix this, also replace manual registrations/unregistration of
framebuffer with devm_register_framebuffer.

Fixes: 68a2d20b79b1 ("drivers/video: add Hyper-V Synthetic Video Frame Buffer Driver")

Signed-off-by: Saurabh Sengar 
Reviewed-by: Michael Kelley 
Tested-by: Michael Kelley 
Link: https://lore.kernel.org/r/1740845791-19977-3-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Wei Liu 
Message-ID: <1740845791-19977-3-git-send-email-ssengar@linux.microsoft.com>

fbdev: hyperv_fb: Simplify hvfb_putmem

2025-03-09T23:56:29+00:00

The device object required in 'hvfb_release_phymem' function
for 'dma_free_coherent' can also be obtained from the 'info'
pointer, making 'hdev' parameter in 'hvfb_putmem' redundant.
Remove the unnecessary 'hdev' argument from 'hvfb_putmem'.

Signed-off-by: Saurabh Sengar 
Reviewed-by: Michael Kelley 
Tested-by: Michael Kelley 
Link: https://lore.kernel.org/r/1740845791-19977-2-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Wei Liu 
Message-ID: <1740845791-19977-2-git-send-email-ssengar@linux.microsoft.com>

fbdev: hyperv_fb: Fix hang in kdump kernel when on Hyper-V Gen 2 VMs

2025-03-09T23:54:10+00:00

Gen 2 Hyper-V VMs boot via EFI and have a standard EFI framebuffer
device. When the kdump kernel runs in such a VM, loading the efifb
driver may hang because of accessing the framebuffer at the wrong
memory address.

The scenario occurs when the hyperv_fb driver in the original kernel
moves the framebuffer to a different MMIO address because of conflicts
with an already-running efifb or simplefb driver. The hyperv_fb driver
then informs Hyper-V of the change, which is allowed by the Hyper-V FB
VMBus device protocol. However, when the kexec command loads the kdump
kernel into crash memory via the kexec_file_load() system call, the
system call doesn't know the framebuffer has moved, and it sets up the
kdump screen_info using the original framebuffer address. The transition
to the kdump kernel does not go through the Hyper-V host, so Hyper-V
does not reset the framebuffer address like it would do on a reboot.
When efifb tries to run, it accesses a non-existent framebuffer
address, which traps to the Hyper-V host. After many such accesses,
the Hyper-V host thinks the guest is being malicious, and throttles
the guest to the point that it runs very slowly or appears to have hung.

When the kdump kernel is loaded into crash memory via the kexec_load()
system call, the problem does not occur. In this case, the kexec command
builds the screen_info table itself in user space from data returned
by the FBIOGET_FSCREENINFO ioctl against /dev/fb0, which gives it the
new framebuffer location.

This problem was originally reported in 2020 [1], resulting in commit
3cb73bc3fa2a ("hyperv_fb: Update screen_info after removing old
framebuffer"). This commit solved the problem by setting orig_video_isVGA
to 0, so the kdump kernel was unaware of the EFI framebuffer. The efifb
driver did not try to load, and no hang occurred. But in 2024, commit
c25a19afb81c ("fbdev/hyperv_fb: Do not clear global screen_info")
effectively reverted 3cb73bc3fa2a. Commit c25a19afb81c has no reference
to 3cb73bc3fa2a, so perhaps it was done without knowing the implications
that were reported with 3cb73bc3fa2a. In any case, as of commit
c25a19afb81c, the original problem came back again.

Interestingly, the hyperv_drm driver does not have this problem because
it never moves the framebuffer. The difference is that the hyperv_drm
driver removes any conflicting framebuffers *before* allocating an MMIO
address, while the hyperv_fb drivers removes conflicting framebuffers
*after* allocating an MMIO address. With the "after" ordering, hyperv_fb
may encounter a conflict and move the framebuffer to a different MMIO
address. But the conflict is essentially bogus because it is removed
a few lines of code later.

Rather than fix the problem with the approach from 2020 in commit
3cb73bc3fa2a, instead slightly reorder the steps in hyperv_fb so
conflicting framebuffers are removed before allocating an MMIO address.
Then the default framebuffer MMIO address should always be available, and
there's never any confusion about which framebuffer address the kdump
kernel should use -- it's always the original address provided by
the Hyper-V host. This approach is already used by the hyperv_drm
driver, and is consistent with the usage guidelines at the head of
the module with the function aperture_remove_conflicting_devices().

This approach also solves a related minor problem when kexec_load()
is used to load the kdump kernel. With current code, unbinding and
rebinding the hyperv_fb driver could result in the framebuffer moving
back to the default framebuffer address, because on the rebind there
are no conflicts. If such a move is done after the kdump kernel is
loaded with the new framebuffer address, at kdump time it could again
have the wrong address.

This problem and fix are described in terms of the kdump kernel, but
it can also occur with any kernel started via kexec.

See extensive discussion of the problem and solution at [2].

[1] https://lore.kernel.org/linux-hyperv/20201014092429.1415040-1-kasong@redhat.com/
[2] https://lore.kernel.org/linux-hyperv/BLAPR10MB521793485093FDB448F7B2E5FDE92@BLAPR10MB5217.namprd10.prod.outlook.com/

Reported-by: Thomas Tai 
Fixes: c25a19afb81c ("fbdev/hyperv_fb: Do not clear global screen_info")
Signed-off-by: Michael Kelley 
Link: https://lore.kernel.org/r/20250218230130.3207-1-mhklinux@outlook.com
Signed-off-by: Wei Liu 
Message-ID: <20250218230130.3207-1-mhklinux@outlook.com>

fbdev: hyperv_fb: iounmap() the correct memory when removing a device

2025-02-21T19:45:02+00:00

When a Hyper-V framebuffer device is removed, or the driver is unbound
from a device, any allocated and/or mapped memory must be released. In
particular, MMIO address space that was mapped to the framebuffer must
be unmapped. Current code unmaps the wrong address, resulting in an
error like:

[ 4093.980597] iounmap: bad address 00000000c936c05c

followed by a stack dump.

Commit d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for
Hyper-V frame buffer driver") changed the kind of address stored in
info->screen_base, and the iounmap() call in hvfb_putmem() was not
updated accordingly.

Fix this by updating hvfb_putmem() to unmap the correct address.

Fixes: d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver")
Signed-off-by: Michael Kelley 
Reviewed-by: Saurabh Sengar 
Link: https://lore.kernel.org/r/20250209235252.2987-1-mhklinux@outlook.com
Signed-off-by: Wei Liu 
Message-ID: <20250209235252.2987-1-mhklinux@outlook.com>