Marc Kleine-Budde 197656de8d can: mcp251xfd: mcp251xfd_chip_wait_for_osc_ready(): improve chip detection and error handling
The function mcp251xfd_chip_wait_for_osc_ready() polls the Oscillator
Control Register for the oscillator to get ready.

This is the first register the driver reads from. Reading implausible
values (all bits set or unset) can be caused by the chip starting up
after power on, waking up after sleep, or by the chip not being preset
at all. Add check for implausible register content
mcp251xfd_reg_invalid() to the regmap_read_poll_timeout() loop.

In case of a regmap_read_poll_timeout() returns a fatal error (and not
a timeout), forward it to the caller.

As mcp251xfd_chip_wait_for_osc_ready() will be called after the probe
function has finished, (currently during ifup), move error message
about failed chip detection from there into the probe function.

Link: https://lore.kernel.org/all/20220207131047.282110-8-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2022-02-24 08:46:58 +01:00
2022-02-13 12:13:30 -08:00

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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