e36c7e9898
The sys_pll on the EC-100 board is configured to 1584MHz at boot (either by u-boot, firmware or chip defaults). This is achieved by using M = 66, N = 1 (24MHz * 66 / 1). At boot the CPU clock is running off sys_pll divided by 2 which results in 792MHz. Thus M = 66 is considered to be a "safe" value for Meson8b. To achieve 1608MHz (one of the CPU OPPs on Meson8 and Meson8m2) we need M = 67, N = 1. I ran "stress --cpu 4" while infinitely cycling through all available frequencies on my Meson8m2 board and could not spot any issues with this setting (after ~12 hours of running this). On Meson8, Meson8b and Meson8m2 we also want to be able to use 408MHz and 816MHz CPU frequencies. These can be achieved by dividing sys_pll by 4 (for 408MHz) or 2 (for 816MHz). That means that sys_pll has to run at 1632MHz which can be generated using M = 68, N = 1. Similarily we also want to be able to use 1008MHz as CPU frequency. This means that sys_pll has to run either at 1008MHz or 2016MHz. The former would result in an M value of 42, which is lower than the smallest value used by the 3.10 GPL kernel sources from Amlogic (50 is the lower limit there). Thus we need to run sys_pll at 2016MHz which can ge generated using M = 84, N = 1. I tested M = 68 and M = 84 on my Meson8b Odroid-C1 and my Meson8m2 board by running "stress --cpu 4" while infinitely cycling thorugh all available frequencies. I could not spot any issues after ~12 hours of running this. Amlogic's 3.10 GPL kernel sources have more M/N combinations. I did not add them yet because M = 74 (to achieve close to 1800MHz on Meson8) and M = 82 (to achieve close to 1992MHz on Meson8 as well) caused my Meson8m2 board to hang randomly. It's not clear why this is (for example because the board's voltage regulator design is bad, some missing bits for these values in our clk-pll driver, etc.). Thus the following M values from the Amlogic 3.10 GPL kernel sources are skipped as of now: 69, 70, 71, 72, 73, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98 Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> Acked-by: Jerome Brunet <jbrunet@baylibre.com> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Link: https://lkml.kernel.org/r/20181115224048.13511-5-martin.blumenstingl@googlemail.com |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| 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.