mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
synced 2026-11-10 20:48:12 +00:00
No description
- C 96.8%
- Assembly 0.9%
- Rust 0.7%
- Shell 0.6%
- Python 0.5%
- Other 0.3%
3028583d13Changing voltage might ignore slew rate and cause a current surge. With current implementation the driver will get the regulator to change the voltage range used during run time. According to communication I have had with Texas Instruments, this is not intended, since the Dynamic Voltage Scaling in the hardware is only designed to work within a voltage range. The current implementation will therefore ignore the slew rate that is defined in devicetree when the voltage range is changed during use. The current implementation will always select a voltage in the most accurate range that can reach that voltage even though multiple ranges are able to reach that voltage. There are 4 Voltage ranges with the following reach: 0b00: 0.4-0.71875V (1.25mV step size) 0b01: 0.4-1.0375V (2.5mV) 0b10: 0.4-1.675V (5mV) 0b11: 0.8-3.3V (10mV) This in practice means that a change from below to above 0.71875V will use the smallest range(0b00) for the values below and the second smallest range(0b01) for the voltages above (Up to 1.675V). I have timed how long it takes to go from below 0.71875V to above. The increase was 100mV which, with the slew rate set to 1250µV/µs. This in theory should take 80µs to do. With the current implementation, it takes 10µs on my hardware. Doing the same test with the slew rate set to 5000µV/µs, which should take 20µs, also only takes 10µs to do on my hardware. Not only is this not in line with the technical specification for the regulator. It also causes a current surge. Which when calculating the output current, as described in the technical specification, compared to what I could observe on my hardware the real output is ~1A higher (~1.2A) than what I calculated it to be(~0.2A). I tested also transitioning from a bigger to a smaller range, and the results were the same. Instead, let's limit the voltage range to a single one, which is in line with the intended use of the regulator. This is done by looking up the minimum and maximum requested voltage specified in devicetree. Signed-off-by: Jonas Andreasson <jonas.andreasson@axis.com> Link: https://patch.msgid.link/20250121-tps-fix-v2-1-50cc4d0f1635@axis.com Signed-off-by: Mark Brown <broonie@kernel.org> |
History
|
|
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| 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 reStructuredText 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.