mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
7c4bada12d
The probe routine acquires the reset GPIO using GPIOD_OUT_LOW. Directly afterwards it calls acx565akm_detect(), which sets the GPIO value to HIGH. If the bootloader initialized the GPIO to HIGH before the probe routine was called, there is only a very short time period of a few instructions where the reset signal is LOW. Exact time depends on compiler optimizations, kernel configuration and alignment of the stars, but I expect it to be always way less than 10us. There are no public datasheets for the panel, but acx565akm_power_on() has a comment with timings and reset period should be at least 10us. So this potentially brings the panel into a half-reset state. The result is, that panel may not work after boot and can get into a working state by re-enabling it (e.g. by blanking + unblanking), since that does a clean reset cycle. This bug has recently been hit by Ivaylo Dimitrov, but there are some older reports which are probably the same bug. At least Tony Lindgren, Peter Ujfalusi and Jarkko Nikula have experienced it in 2017 describing the blank/unblank procedure as possible workaround. Note, that the bug really goes back in time. It has originally been introduced in the predecessor of the omapfb driver in commit |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.