Heiko Stuebner b20150d499 clk: check for disabled clock-provider in of_clk_get_hw_from_clkspec()
of_clk_get_hw_from_clkspec() checks all available clock-providers by
comparing their of nodes to the one from the clkspec. If no matching
clock provider is found, the function returns -EPROBE_DEFER to cause a
re-check at a later date. If a matching clock provider is found, an
authoritative answer can be retrieved from it whether the clock exists
or not.

This does not take into account that the clock-provider may never
appear, because it's node is disabled. This can happen when a clock is
optional, provided by a separate block which never gets enabled.

One example of this happening is the rk3588's VOP, which has optional
additional display clocks coming from PLLs inside the hdmiphy blocks.
These can be used for better rates, but the system will also work
without them.

The problem around that is described in the followups to[1]. As we
already know the of node of the presumed clock provider, add a check via
of_device_is_available() whether this is a "valid" device node. This
prevents eternal defer loops.

Link: https://lore.kernel.org/dri-devel/20250215-vop2-hdmi1-disp-modes-v1-3-81962a7151d6@collabora.com/ [1]
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Tested-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20250222223733.2990179-1-heiko@sntech.de
[sboyd@kernel.org: Reword commit text a bit]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2025-02-26 14:33:15 -08:00
2024-09-01 20:43:24 -07:00
2022-09-28 09:02:20 +02:00
2025-02-02 15:39:26 -08:00
2024-03-18 03:36:32 -06:00

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 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.
Description
No description provided
Readme 3.4 GiB
Languages
C 97%
Assembly 1%
Shell 0.6%
Rust 0.5%
Python 0.4%
Other 0.3%