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Filename Latest commit message Latest commit date
Yifeng Li 9e0e59993d fbdev: sm712fb: fix crashes during framebuffer writes by correctly mapping VRAM
On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), running fbtest or X
will crash the machine instantly, because the VRAM/framebuffer is not
mapped correctly.

On SM712, the framebuffer starts at the beginning of address space, but
SM720's framebuffer starts at the 1 MiB offset from the beginning. However,
sm712fb fails to take this into account, as a result, writing to the
framebuffer will destroy all the registers and kill the system immediately.
Another problem is the driver assumes 8 MiB of VRAM for SM720, but some
SM720 system, such as this IBM Thinkpad, only has 4 MiB of VRAM.

Fix this problem by removing the hardcoded VRAM size, adding a function to
query the amount of VRAM from register MCR76 on SM720, and adding proper
framebuffer offset.

Please note that the memory map may have additional problems on Big-Endian
system, which is not available for testing by myself. But I highly suspect
that the original code is also broken on Big-Endian machines for SM720, so
at least we are not making the problem worse. More, the driver also assumed
SM710/SM712 has 4 MiB of VRAM, but it has a 2 MiB version as well, and used
in earlier laptops, such as IBM Thinkpad 240X, the driver would probably
crash on them. I've never seen one of those machines and cannot fix it, but
I have documented these problems in the comments.

Signed-off-by: Yifeng Li <tomli@tomli.me>
Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Teddy Wang <teddy.wang@siliconmotion.com>
Cc: <stable@vger.kernel.org>  # v4.4+
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
2019-04-01 17:46:59 +02:00
arch A collection of x86 and ARM bugfixes, and some improvements to documentation. 2019-03-31 08:55:59 -07:00
block blk-mq: fix sbitmap ws_active for shared tags 2019-03-25 13:05:47 -06:00
certs
crypto lib/lzo: separate lzo-rle from lzo 2019-03-07 18:32:03 -08:00
Documentation A collection of x86 and ARM bugfixes, and some improvements to documentation. 2019-03-31 08:55:59 -07:00
drivers fbdev: sm712fb: fix crashes during framebuffer writes by correctly mapping VRAM 2019-04-01 17:46:59 +02:00
fs Merge branch 'akpm' (patches from Andrew) 2019-03-29 16:02:28 -07:00
include udlfb: introduce a rendering mutex 2019-04-01 17:46:57 +02:00
init init/main: add checks for the return value of memblock_alloc*() 2019-03-12 10:04:02 -07:00
ipc Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-03-12 14:08:19 -07:00
kernel Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-03-31 08:22:12 -07:00
lib for-linus-20190329 2019-03-29 14:43:07 -07:00
LICENSES
mm mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate 2019-03-29 10:01:37 -07:00
net A patch to avoid choking on multipage bvecs in the messenger and 2019-03-29 14:41:09 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-03-11 08:54:01 -07:00
scripts Merge branch 'akpm' (patches from Andrew) 2019-03-29 16:02:28 -07:00
security LSM: Revive CONFIG_DEFAULT_SECURITY_* for "make oldconfig" 2019-03-29 14:08:49 -07:00
sound sound fixes for 5.1-rc3 2019-03-29 14:53:33 -07:00
tools A collection of x86 and ARM bugfixes, and some improvements to documentation. 2019-03-31 08:55:59 -07:00
usr
virt KVM/ARM fixes for 5.1 2019-03-28 19:07:30 +01:00
.clang-format Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-03-12 13:43:42 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap mailmap: add Changbin Du 2019-03-29 10:01:37 -07:00
COPYING
CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig
MAINTAINERS Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-03-31 07:48:58 -07:00
Makefile Linux 5.1-rc3 2019-03-31 14:39:29 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.