Roman Stratiienko 4167ac8a65 clk: sunxi-ng: sun50i: h6: Modify GPU clock configuration to support DFS
Using simple bash script it was discovered that not all CCU registers
can be safely used for DFS, e.g.:

    while true
    do
        devmem 0x3001030 4 0xb0003e02
        devmem 0x3001030 4 0xb0001e02
    done

Script above changes the GPU_PLL multiplier register value. While the
script is running, the user should interact with the user interface.

Using this method the following results were obtained:

| Register  | Name           | Bits  | Values | Result |
| --        | --             | --    | --     | --     |
| 0x3001030 | GPU_PLL.MULT   | 15..8 | 20-62  | OK     |
| 0x3001030 | GPU_PLL.INDIV  |     1 | 0-1    | OK     |
| 0x3001030 | GPU_PLL.OUTDIV |     0 | 0-1    | FAIL   |
| 0x3001670 | GPU_CLK.DIV    |  3..0 | ANY    | FAIL   |

DVFS started to work seamlessly once dividers which caused the
glitches were set to fixed values.

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220705075226.359475-1-r.stratiienko@gmail.com
2022-07-08 18:13:50 +02:00
2022-06-05 17:18:54 -07:00

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.
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